Nakshatras of 63 Nayanmars, 12 Alvars, 18 Siddhars, 7 Saptharishis

This article will be a compilation of the birth information of holy beings who were associated with divine deities in some way or other through their selfless devotion and steadfast worship. They have contributed immensely to tradition and history at large through their forte in multidimensional fields spanning across Music, Dance, Yoga, Art, Science, Alchemy, Astronomy, Astrology, Medicine, Manuscripts and a host of other literary masterpieces. Notwithstanding their phenomenal oeuvre and massive contributions that have led to mankind being blessed with literary materials in abundance, they were always devoted taking refuge at the feet of the Lord and dedicating all their achievements to the higher spiritual realm. Lets look at the list of these saintly doyens and document their associated Nakshatra/Birth Information.

63 Nayanmars
The Nayanmars or the Nayanars as they are called were a group of 63 Shaivite Tamil poet saints who were believed to have lived roughly between around the 6th to 9th century. They were known largely for their decorated veneration towards Lord Shiva by singing his hymns and praises across numerous Shiva temples. Listed below is the list of Nayanars along with their birth Nakshatra

1) Thiru Nilakanda Nayanar – Thai – Visagam / Vishakha
2) Iyarpakai Nayanar – Margazhi – Uthiram / Uttara Phalguni
3) Ilayankudimara Nayanar – Avani – Magam / Magha
4) Meypporul Nayanar – Karthikai – Uthiram / Uttara Phalguni
5) Viranminda Nayanar – Chithirai – Thiruvadhirai / Aarudra
6) Amarnidhi Nayanar – Ani – Pooram / Poorva Phalguni
7) Eripaththa Nayanar – Masi – Hastham / Hastha
8) Enathinatha Nayanar – Purattasi – Uthiram / Uttara Phalguni
9) Kannappa Nayanar – Thai – Mrigaseerisham / Mrigashira
10) Kunkiliyak Kalaya Nayanar – Avani – Moolam / Moola
11) Manak Kanychara Nayanar – Markazhi – Swathi
12) Arivattaya Nayanar – Thai – Thiruvadhirai / Aarudra
13) Anaya Nayanar – Karthikai – Hastham / Hastha
14) Murthi Nayanar – Adi – Karthigai / Krithika
15) Muruga Nayanar – Vaikasi – Moolam / Moola
16) Uthira Pasupathi Nayanar – Purattasi – Ashwini
17) Thirunalai Povar Nayanar – Purattasi – Rohini
18) Thirukkuripputh Thondar Nayanar –Chithirai – Swathi
19) Chandicha Nayanar – Thai – Uthiram / Uttara Phalguni
20) Thiru Navukkarasar Nayanar – Chithirai – Sadayam / Satabhisha
21) Kulachirai Nayanar – Avani – Anusham / Anuradha
22) Perumizalai Kurumba Nayanar – Adi – Chithirai / Chitra
23) Karaikkal Ammayar Nayanar – Panguni – Swathi
24) Appoodhi Adikalar Nayanar – Thai – Sadayam / Satabhisha
25) Thiru Nilakanda Nayanar – Vaikasi – Moolam / Moola
26) Naminadhi Nayanar – Vaikasi – Poosam / Pushya
27) Thiru Gnana Sambandhar Nayanar – Vaikasi – Moolam / Moola
28) Eyarkon Kalikamar Nayanar – Ani – Revathi
29) Thirumoola Nayanar – Aippasi – Ashwini
30) Dhandiyadikal Nayanar – Panguni – Sadayam / Satabhisha
31) Moorkka Nayanar – Karthikai – Moolam / Moola
32) Chomachimara Nayanar – Vaikasi – Aayilyam / Ashlesha
33) Chakkiya Nayanar – Margazhi – Pooradam / Poorva Ashada
34) Chirappuli Nayanar – Karthikai – Pooradam / Poorva Ashada
35) Chiruthonda Nayanar – Chithirai – Bharani
36) Kazarirru Arivar Nayanar /Cheraman Perumal Nayanar – Adi – Swathi
37) Gana Nadha Nayanar – Panguni – Thiruvadhirai / Aarudra
38) Kurruva Nayanar – Adi – Thiruvadhirai / Aarudra
39) Pugazh Chozha Nayanar – Adi – Karthigai / Krithika
40) Narchinga Munaiyaraiya Nayanar – Purattasi – Sadayam / Satabhisha
41) Adhipaththa Nayanar – Avani – Aayilyam / Ashlesha
42) Kalikkamba Nayanar – Thai – Revathi 
43) Kaliya Nayanar – Adi – Kettai / Jyeshta
44) Chaththi Nayanar – Aippasi – Poosam / Pushya
45) Aiyadikal Kadavar Kon Nayanar – Aippasi – Moolam / Moola
46) Kanampulla Nayanar – Karthikai – Karthigai / Krithika
47) Kari Nayanar – Masi – Pooradam / Poorva Ashada
48) Ninra Chir Nedumara Nayanar – Aippasi – Bharani
49) Vayilar Nayanar – Margazhi – Revathi
50) Munaiyaduyar Nayanar – Panguni – Poosam / Pushya
51) Kazharchinka Nayanar – Vaikasi – Bharani
52) Idankazhi Nayanar – Aippasi – Karthikai – Karthigai / Krithika
53) Cheruththunai Nayanar – Avani – Poosam / Pushya
54) Pugazh Thunai Nayanar – Avani – Aayilyam / Ashlesha
55) Kotpuli Nayanar – Adi – Kettai / Jyeshta
56) Pusalar Nayanar – Aippasi – Anusham
57) Mangayar Karasiyar Nayanar – Chithirai – Rohini
58) Nesa Nayanar – Panguni – Rohini
59) Kochengat Chozha Nayanar – Masi – Sadayam / Satabhisha
60) Thiru Nilakanda Yazhppana Nayanar – Vaikasi – Moolam / Moola
61) Sadaiya Nayanar – Markazhi – Thiruvadhirai / Aarudra
62) Isaignaniyar Nayanar – Chithirai – Chithirai / Chitra
63) Sundaramurthy Nayanar – Adi – Swathi

The names of the Nayanars were first compiled by Sundarar (Sundaramurthy Nayanar) and later expanded by Nambiyandar Nambi in the 10th century who included Sundarar also in the canonical list as #63. There are also said to be 275 Paadal Petra Sthalams which are said to be the Shiva temples glorified through devotional verses and poetic hymns composed by the Nayanars. This list also became 276 later with the introduction of an additional Shiva temple called Thiruvidaivayil as its believed that initially the manuscripts were missing and once the authentic verses happened to be discovered, it was integrated by the scholars and the tally extended to 276. Out of these 63 Nayanars, 3 of them happen to be females viz Karaikkal Amaiyyar (#23), Mangayar Karasiyar (#57) and Isaignaniyar (#62). Isaignaniyar's husband Sadaiya Nayanar (#61) and son Sundaramurthy (#63) also form part of the list of Nayanmars.

While there are 63 Nayanars, the initial 275 temples are specifically identified and designated by the work of 3 of the Nayanars. The hymns composed by these three Nayanars are compiled into the first seven volumes of the Shaivite holy canon known as the Tevaram. The 3 Saints are by themselves identified as the Moovar (translated as "The Three Great Saints"). The Moovars are namely:
- Thiru Gnana Sambandhar Nayanar (#27 in above list of 63)
- Thiru Navukkarasar Nayanar also known popularly as "Appar" (#20 in above list of 63)
- Sundaramurthy Nayanar also known as "Sundarar" (#63 in above list of 63)

There is however one prominent saint called Manickavasagar who is missed out in the list of 63 Nayanars and not considered as one of the Nayanars. This is because Saint Manickavasagar's timing fell outside the list of 63 Nayanars compiled by Nambiyandar Nambi around the 10th century. Manickavasagar's entry was at a slightly later point in time and he instead gets grouped under the status of  the "Naalvar" (Translated as the 4 great saints). The author "Sekkizhar" in his 12th century work titled "Periya Puranam" mentions the 4 names which includes the 3 Moovars plus Manickavasagar. Thus the Naalvar consists of the 3 major Tevaram hymnists alongside Manickavasagar who penned the literary work of Thiruvasagam. In almost all of the 275 Paadal Petra Sthalams, you can witness dedicated shrines of most Nayanars and especially the 4 hallowed saints termed as the "Naalvar". The 4 preceptors or Naalvars are listed below:
- Thiru Gnana Sambandhar Nayanar also known as "Sambandhar" (#27 in above list of 63)
- Thiru Navukkarasar Nayanar also known popularly as "Appar" (#20 in above list of 63)
- Sundaramurthy Nayanar also known as "Sundarar" (#63 in above list of 63)
- Manickavasagar originally coined as "Vadavoorar" (Not part of the list of Nayanars but grouped under "Naalvar" by Sekkizhar in Periya Puranam)

Thus, we have 63 Nayanars and additionally Manickavasagar who is not part of the list of 63. Later, there have also been references of a 64th Nayanar added in the form of the venerated Tamil Poet "Thiruvalluvar" from Mylapore who is known for penning the majestic work of "Thirukkural". However most popular rosters list only the 63 Nayanars and there is no place specifically for Manickavasagar or Thiruvalluvar as their time period was outside the list initially compiled as 63. Lets however document the Nakshatra information of both Manickavasagar and Thiruvalluvar along with Deiva Sekkizhar who was a 12th century poet who authored "Periya Puranam" detailing the lives of the 63 famous Shiva devotees or Nayanmars and also that of the scholar Nambiyandar Nambi who initially compiled the list of 63 Nayanars in the "Tevaram" which later became the basis for Sekkizhar to author the "Periya Puranam". Also documenting the information of the great King Raja Raja Chozha who was a contemporary of Nambiyandar Nambi. The King requested Nambiyandar Nambi to compile the lost Shaivite Thirumurais and hence he was also instrumental in recovering the divine hymns composed by the Nayanars. The King's son Rajendra Chozha, another great Chozha emperor was also a great Shiva Bhakta and responsible for the construction of the iconic Gangaikonda Cholapuram temple.

One more thing to note is that in many of the cases listed of the Nayanars, the Nakshatra information may not be the one in which these great saints historically took birth due to lack of recording the same but can be linked to their Guru Pooja day which is when they attained mukti and became one with the Gods. Many of the traditional celebrations and primary day observed of the Nayanars is linked largely to their liberation day.
- Manickavasagar – Ani – Magam / Magha
- Thiruvalluvar - Vaikasi – Anusham / Anuradha
- Deiva Sekkizhar - Vaikasi – Poosam / Pushya
- Nambiyandar Nambi –  Vaikasi – Punarpoosam / Punarvasu
- Sri Raja Raja Chozha –  Aippasi – Sadayam / Satabhisha
- Sri Rajendra Chozha – Adi – Thiruvadhirai / Aarudra

There is an additional important grouping to be noted especially relating to the Naalvars of the Nayanars. The Naalvars also belong to a classification called as 'Kuravars' who are known for being spiritual teachers, preceptors and enlightened souls. Kuravars by themselves are divided into 2 groupings namely Samaya Kuravars and Santhana Kuravars. The Nalvars are also called as the "4 Samaya Kuravars" and are said to be preceptors of religion and devotion. Another category of "Kuravars" are termed as the "4 Santhana Kuravars" mentioned to be preceptors of philosophy and lineage. The Santhana Kuravars are again classified into 2 groups of 4 each termed as "Agach Santhana Kuravar" and "Purach Santhana Kuravar". The former relates to the inner or celestial lineage and are said to reside in Mount Kailash whereas the latter pertains to the outer or earthly lineage referring to scholars who lived on Mother Earth. The Agach Santhana Kuravars are believed to have received the ultimate truth directly from the source of wisdom and knowledge of Lord Dakshinamurthy who is an aspect of Lord Shiva himself. The Purach Santhana Kuravars were human saints and erudite scholars who walked the earth and spread knowledge. The Purach Santhana Kuravars or just Santhana Kuravars as they are usually quoted are said to have lived around 500 years later than the Samaya Kuravars / Naalvars in about the 13th to 14th century. Listing below the birth information of the Purach Santhana Kuravars
- Meykandar – Aippasi – Anusham / Anuradha
- Arul Nandhi Shivam – Purattasi – Pooram / Poorva Phalguni
- Maraignana Sambandhar – Avani – Uthiram / Uttara Phalguni
- Umapathi Shivachariyar – Chithirai – Hastham / Hastha

Thus, to summarize on the Kuravars. Kuravars are of 2 categories viz Shaiva Samaya Kuravars and Shaiva Santhana Kuravars. The Santhana Kuravars are further divided into 2 sub classifications of 4 each known as Agach Santhana Kuravars and Purach Santhana Kuravars. Listed below the names of the Samaya Kuravars and the Santhana Kuravars

The Samaya Kuravars also known as Naalvars:
- Thiru Gnana Sambandhar also known as "Sambandhar"
- Thiru Navukkarasar also known as "Appar"
- Sundaramurthy also known as "Sundarar"
- Manickavasagar originally known as "Vadavoorar"

The Agach Santhana Kuravars:
- Thiru Nandi Devar known as being Nandi, Lord Shiva's bull
- Sanath Kumara known to be a mind born son of Lord Brahma
- Satya Gyana Darshini is a celestial saint from the higher realms
- Paranjyoti Munivar is a divine sage who briefly descended to earth to pass on the knowledge

The Purach Santhana Kuravars:
- Meykandar originally born as Tiruvennainallur and mentioned to be a prodigy
- Arul Nandhi Shivam known as Sakalagama Panditar - master of all sacred Agamas
- Maraignana Sambandar known as Kankatti Bandaram due to tying cloth over eyes to control senses
- Umapathi Shivachariyar known as Korravankudi Sivam by the name of his village

Since the saints belonging as part of Agach Santhana Kuravars are said to be divine creations that ascended directly in Mount Kailash and not Earth, there is no birth information about them. The tradition of the Agach Santhana Kuravars is said to begin from Lord Dakshinamurthy. The Adi Guru is said to be the primary Guru of Nandi Devar and Nandi Devar in turn is said to be the Guru of Sanath Kumara and so on. The 4th Agach Kuravar Paranjyoti Munivar however was briefly instructed to descend from Mount Kailash to Earth in order to pass on the knowledge. He discovered a noteworthy disciple in the form of a 2 year old prodigy called Tiruvennainallur. He initiated and invoked the child about the final truth and higher knowledge giving him the title of Meykandar. Thus Meykandar from Purach Santhana Kuravar is said to be the disciple of Paranjyoti Munivar who is said to be the root of knowledge transfer from the group of Agach Santhana Kuravars to Purach Santhana Kuravars. The Purach Santhana Kuravars are together responsible for having penned the Meikanda Shastras which are 14 foundational philosophical texts of Tamil Shaiva Siddhantham.

Additionally, from the list of the Agach Santhana Kuravars, Sanath Kumara is also considered as one of the Kumaras and is grouped under the classification of 'Sanakadi Rishis'. They are said to be mind born sons of Lord Brahma with their life long goal being inclined to the pursuit of learning and spiritual service. These 4 Sages are usually seen under the tutelage of Lord Dakshinamurthy to seek the ultimate truth and get imparted with supreme knowledge. Listed below are the names of the Sanakadi Rishis

The Sanakadi Rishis or 4 Kumaras:
- Sanaka
- Sanandana
- Sanatana
- Sanath Kumara

12 Alvars
In very similar vein to the Nayanars, the Alvars are said to be 12 specific Tamil poet saints who lived between the 5th and 10th century and showcased their deep devotion and admiration to Lord Vishnu in the form of divine hymns and citations. Their extensive work has been compiled in the Naalayira Divya Prabandham consisting of 4000 verses. Like how Nayanars upheld the Shaivite tradition, the Alvars spread the bhakti movement and shaped the Sri Vaishnava tradition. Akin to the 275 Padal Petra Sthalams dedicated to Lord Shiva where Nayanars have potrayed their devotions, here there are 108 temples popularly coined as "Divya Desams" where the Alvars have sung hymns, expressed devotion and paid obeisance to Lord Vishnu. Out of the 108 Divya Desams, only 106 are in the physical realm belonging in Planet Earth with 105 of these located in India and the one located outside India being at Saligramam in Nepal. The two Divya Desams not located on Earth happen to be Kshira Sagara - the divine ocean in Heaven and Vaikunta - the heavenly abode of Vishnu & Lakshmi. Listed below is the list of Alvars along with their Thiru Nakshatra which is the holy birth star of divine manifestations.

1) Poigai Alvar – Aippasi – Tiruvonam / Shravana
2) Bhoothath Alvar – Aippasi– Avittam / Dhanishta
3) Pei Alvar – Aippasi – Sadayam / Satabhisha
4) Thirumalisai Alvar – Thai – Magam / Magha
5) Namm Alvar – Vaikasi – Visagam / Vishakha
6) Madhura Kavi Alvar – Chithirai – Chithirai / Chitra
7) Kulasekara Alvar – Masi – Punarpoosam / Punarvasu
8) Periya Alvar – Ani – Swathi
9) Andal Alvar – Adi – Pooram / Poorva Phalguni
10) Thondaradipodi Alvar – Margazhi – Kettai / Jyeshta
11) Thiruppan Alvar – Karthikai – Rohini
12) Thiru Mangai Alvar – Karthikai – Karthigai / Krithika

Out of the 12 Alvars, the only solitary female saint happens to be Devi Andal. In fact Andal is also the most well known of the Alvars and commands separate deity worship in most Vaishnava temples. Her effusive devotion and profusive love towards Lord Ranganatha is said to be unparalleled and expressed in reverence through her divine pasurams. All the 12 Alvars are also associated with a symbol of Lord Vishnu and represent a form or avatar of Vishnu. Lets look at the symbolic connection of Alvars with Lord Vishnu:
- Poigai Alvar – Panchajanya (Vishnu's Conch)
- Bhoothath Alvar – Kaumodaki (Vishnu's Mace)
- Pei Alvar – Nandaka (Vishnu's Sword)
- Thirumalisai Alvar – Sudarshana Chakra (Vishnu's Discus)
- Namm Alvar – Vishwak Sena (Vishnu's Commander)
- Madhura Kavi Alvar – Padma (Vishnu's Lotus)
- Kulasekara Alvar – Kaustubha (Vishnu's Necklace)
- Periya Alvar – Garuda (Vishnu's Mount)
- Andal Alvar – Bhoo Devi (Vishnu's wife, the Earth Goddess)
- Thondaradipodi Alvar – Vanamalai (Vishnu's Garland)
- Thiruppan Alvar – Srivatsa (Vishnu's Chest consisting of an auspicious mark)
- Thiru Mangai Alvar – Saranga (Vishnu's Bow)

Apart from the Alvars, there were also few other prominent personalities who propagated and spread the Vaishnava philosophy. Though, they may not be classified or acknowledged as one among the Alvars, they are still very widely revered and venerated by the Vaishnava community. Sriman Nathamuni is credited for resurrecting the lost 4000 Divya Prabandhams. Swami Alavandar also known as Yamunacharya is the grandson of Nathamuni and widely known as the grand guru of Ramanuja setting the groundwork for Advaita philosophy and also penned the Stotra Ratnam. Sri Thirukkottiyur Nambi also called Goshti Purana was a renowned guru who tested Sri Ramanujacharya eighteen times before revealing the inner meanings of sacred mantras. Sri Periya Nambi also known as Purna Acharya is the main guru of Ramanuja who was instrumental in initiating him into the Vaishnava fold. Sri Koorath Azhwan also known as Kuresa was the primary disciple of Ramanuja and is believed to have saved him from a Chola King, also known for being an incarnation of Vishnu's mark on his chest "Srivatsa". Ramanujacharya is considered as a great reformer and central proponent of the Vaishnava philosophy. Sri Ananth Azhwan also known as Ananta Acharya was a devoted disciple whom Sri Ramanujacharya sent to Tirumala to establish a flower garden for Lord Venkateswara Swamy. Engal Azhwan also called Vishnuchitta was a noted scholar who wrote commentaries on the Vishnu Purana. Swami Mudali Andan also known as Dasarathi is considered as one of the foremost disciples of Ramanujacharya and also mentioned to be an incarnation of Lord Rama is known for establishing Pancha Narayana temples as per the instruction of his Guru. Parashara Bhattar, the son of Koorathazhwan is said to have written the commentary for the definitive Vishnu Sahasranamam. Vedanta Desikar also known as Venkatanatha is believed to have revived sacred texts and known for many religious and poetic works and also said to be an Avatar of Ghanta, the bell pertaining to Sri Venkateshwara Perumal Temple of Tirumala. Manavala Mamunigal is widely celebrated in temples like Srirangam and is also believed to be a manifestation of the divine serpent Adishesha. Lets take a look at the birth information of these famous Vaishnava saints.
- Sriman Nathamuni – Ani – Anusham / Anuradha
- Swami Alavandar – Adi – Uthiradam / Uttara Ashada
- Sri Thirukkottiyur Nambi – Vaikasi – Rohini
- Sri Periya Nambi – Margazhi – Kettai / Jyeshta
- Sri Koorath Azhwan – Thai – Hastham / Hastha
- Sri Ramanujacharya – Chithirai – Thiruvadhirai / Aarudra
- Sri Ananth Azhwan – Chithirai – Chithirai / Chitra
- Sri Engal Azhwan – Chithirai – Rohini
- Swami Mudali Andan – Chithirai – Punarpoosam / Punarvasu
- Parashara Bhattar – Vaikasi – Anusham / Anuradha
- Vedanta Desikar – Purattasi – Tiruvonam / Shravana
- Sri Manavala Mamunigal – Aippasi – Moolam / Moola

18 Siddhars
In the Tamil Siddha tradition, 18 sages are mentioned as prominent and are said to have lived during the times of the Gods dating way back to the time when the epics Ramayana & Mahabharatha were scripted. They are said to have made pioneering progress in a significant number of fields. These Siddhars are also known for their staunch devotion to the divine and have even been like a guiding force to the deities. There are mythological stories of the Siddhars consecrating the Linga at various temples and performing worship. They are also known to be mystical and are said to have transcended across time periods with some of them even living across multiple yugas. Unlike the list of the 63 Nayanars or the 12 Alvars, when it comes to the Siddhars there are various variations witnessed and recorded. Different temples have different 18 Siddhars as representations but however majority of them tend to tally across various lists with just a few variances here and there. Sharing below the most common list of 18 Siddhars and their relevant birth information. The listing below is from Arulmigu Sri Kolanjiappan temple at Virudachalam in Cuddalore district which is dedicated mainly to Lord Murugan. Not only are their carvings of the 18 Siddhars here, but it also describes details for each of them such as birth Nakshatra, solar month, time of living period and their place of Jeeva Samadhi.  

1) Agathiyar Siddhar – Margazhi – Aayilyam / Ashlesha
2) Patanjali Siddhar – Panguni – Moolam / Moola
3) Thirumoolar Siddhar – Purattasi – Avittam / Dhanishta
4) Kamalamuni Siddhar – Vaikasi – Poosam/ Pushya
5) Kudambai Siddhar – Adi – Visagam / Vishakha
6) Korakkar Siddhar – Karthikai – Aayilyam / Ashlesha
7) Dhanvantri Siddhar – Aippasi – Punarpoosam / Punarvasu
8) Sundarananthar Siddhar – Avani – Revathi
9) Konganar Siddhar – Chithirai – Uthiradam / Uttara Ashada
10) Sattaimuni Siddhar – Avani – Mrigaseerisham / Mrigashira
11) Valmiki Siddhar – Purattasi – Anusham / Anuradha
12) Ramadevar Siddhar – Masi – Pooram/ Poorva Phalguni
13) Agapeyar Siddhar – Panguni – Mrigaseerisham / Mrigashira
14) Idaikadhar Siddhar – Purattasi – Thiruvadhirai / Aarudra
15) Machamuni Siddhar – Adi – Rohini
16) Karuvurar Siddhar – Chithirai – Hastham / Hastha
17) Bhogar Siddhar – Vaikasi – Bharani
18) Pambatti Siddhar – Karthikai – Mrigaseerisham / Mrigashira

Apart from the list mentioned above, there are some scattered information which replicates the above list ditto except for Agapeyar Siddhar who is replaced by Nandeeswarar Siddhar. There are also few temples in Chennai consisting idols of the 18 Siddhars. Recounting the ones listed in them to tally for the variations.
Thanga Murugan / Palandi Amman Temple, Vanuvampet - Agathiyar, Pambatti, Ramadevar, Pulippani, Kudambai, Bhogar, Azhugunar, Idaikadhar, Konganar, Sattaimuni, Theraiyar, Machamuni, Pulastya, Korakkar, Thirumoolar, Kalanginathar, Karuvurar, Kamalamuni
Annai Adhi Parasakthi Temple, Pallikaranai - Agathiyar, Siva Vakiyar, Bhogar, Pulastya, Kalanginathar, Sattaimuni, Karuvurar, Azhugunar, Theraiyar, Idaikadhar, Machamuni, Konganar, Pulippani, Thirumoolar, Kamalamuni, Ramadevar, Punnakeesar, Pambatti
Chidambara Periya Swamigal Temple, Velachery - Agathiyar, Thirumoolar, Ramadevar, Sundarananthar, Machamuni, Sattaimuni, Bhogar, Korakkar, Karuvurar, Idaikadhar, Konganar, Dhanvantri, Pambatti, Azhugunar, Siva Vakiyar, Kalanginathar, Punnakeesar, Pulippani
Sri Chakra Maha Meru 18 Siddhar Temple, Madambakkam - Pattinathar, Kaduveli, Siva Vakiyar, Kambili, Bhogar, Pulippani, Vallalar, Idaikadhar, Kaga Bhujandhar, Agapeyar, Kanjamalai, Sennimalai, Kapilar, Karuvurar, Azhugunar, Pambatti, Sattaimuni, Kudambai

Thus, from various sources observed it is pretty evident that there are minor variations witnessed. The list of the last mentioned temple Maha Meru is however of the Siddhars associated with the 9 Navagrahas with 2 Siddhars provided for each of the Navagrahas in order of Sun, Moon, Mars, Mercury, Jupiter, Venus, Saturn, Rahu and Ketu. As some names get used interchangeably, documenting below few of the Siddhars birth information not forming part of the original list of 18 above:
- Siva Vakiyar Siddhar – Thai – Magam / Magha
- Kaga Bhujandar Siddhar – Panguni – Uthiram / Uttara Phalguni
- Pulippani Siddhar – Purattasi - Swathi
- Punnakeesar Siddhar – Vaikasi – Chithirai / Chitra
- Kalangi Nathar Siddhar - Chithirai - Ashwini
- Azhugunar Siddhar – Vaikasi – Visagam / Vishakha
- Theraiyar Sidhar – Vaikasi – Aayilyam / Ashlesha
- Nandeeswarar Siddhar – Vaikasi – Visagam / Vishakha
- Vallalar Siddhar – Purattasi - Chithirai / Chitra

Also, there are few Siddhars who do not form part of the traditional 18 Tamil Siddhars list but tend to be associated with certain Nakshatras. Sharing that also below for reference. Please however note that the information may not be completely accurate, it could be either Thiru Nakshatra or the Guru Pooja Day. 
- Vyasa Siddhar – Associated with Jyeshta / Kettai
- Romarishi Siddhar – Associated with Karthigai / Krithika
- Dakshinamurthy Siddhar – Associated with Tiruvonam / Shravana
- Kowbalar Siddhar – Associated with Sadayam / Satabhisha
- Jyoti Muni Siddhar – Associated with Pooratathi / Poorva Bhadrapada
- Damaragar Siddhar – Associated with Uttiratathi / Uttara Bhadrapada
- Pattinathar Siddhar – Associated with Uthiradam / Uttara Ashada
- Kaduveli Siddhar – Associated with Pooradam / Poorva Ashada

7 Saptharishis
Other than the 18 hallowed Siddhars from South, there is also a Rishi tradition termed as 'Saptharishis' known as the 7 divine sages of Hinduism. They are said to be seers embodying divine wisdom and cosmic order. The names of these Rishis keep changing across different cosmic cycles. When it comes to birth information of these venerated Rishis, there isn't much information available especially because these Rishis have transcended across multiple eons. Sharing whatever information that is currently available. As per the current age in existence, the 7 Rishis are listed as below:

1) Vasishta Saptharishi – Vaishakha Shukla Paksha Navami – Poosam / Pushya
2) Vishwamitra Saptharishi – Karthik Shukla Paksha Tritiya – Anusham / Anuradha
3) Gautama Saptharishi – Chaitra Shukla Paksha Pratama – No information on Nakshatra
4) Kashyapa Saptharishi – Jyeshta Shukla Paksha Panchami – No information on Nakshatra
5) Bharadwaja Saptharishi – No specific Bharadwaja Jayanthi – No information on Nakshatra
6) Atri Saptharishi – No specific Atri Jayanthi – No information on Nakshatra
7) Jamadagni Saptharishi – No specific Jamadagni Jayanthi – No information on Nakshatra

Based on observation, it is seen that there is not much birth information recorded for the Saptharishis. Only for Rishi Vasishta and Rishi Vishwamitra, there are sources explicitly mentioning that they were born in Pushya and Anuradha respectively. For other Rishis, there is devoid of information when it comes to birth. Also there are other Rishis also who have been part of the Saptharishis cosmic cycle in earlier existences such as Angiras, Bhrigu, Kratu,Kutsa, Garga, Gungu, Marichi, Pulaha, Pulastya, and few others.

There is a common anniversary which takes place for the Rishis as a whole that happens every year termed as Rishi Jayanthi. Universally the Rishis are celebrated on Rishi Jayanthi or Rishi Panchami as its called which occurs on the 5th waxing day of Panchami in the lunar month of Bhadrapada. It normally tends to take place a day after Ganesh Chaturthi which also is on Bhadrapada month but on the 4th waxing day of Chaturthi.

Documenting Few Other Important References:
As we have covered the 63 Nayanars, 12 Alvars, 18 Siddhars and the 7 Saptharishis in detail along with further references of doyens who lived around their time period who didn't get classified under the title of the above listed categories yet contributed heavily through their works and staunch devotion to the divine. One interesting point to note is that there is only one saint who gets to be a primary part of 2 of the lists above which are the 63 Nayanars and 18 Siddhars which happens to be respected 'Sage Thirumoolar'. He is slotted under #29 in the list of 63 Nayanars and you can also find his name in the Siddhar's list at #3 out of the 18 Tamil Siddhars. Though the Siddha list is not completely consistent, there is no question about Thirumoolar not being part of this sacred tradition. You would note the difference however in his Nakshatra and that is because the one listed under 63 Nayanars is the "Guru Pooja Nakshatra" and the one under 18 Siddhars is the "Thiru Nakshatra". Sage Agasthya could also be considered as someone who's part of the 18 Siddhar list and also the 7 Saptharishis probably in an earlier cosmic cycle.

The Siddhars, Rishis and their connection with Nakshatras & Navagrahas

A Sage from a layman's language can said to be enlightened and elevated mystical beings possessing intense spiritual powers. They are said to have lived during the times of the Gods and hold supernatural abilities on account of undertaking deep spiritual penance. They can almost be reckoned to be an equivalent form of God just that they are not as widely reverent and don't have the adulation that the divine commands in places of worship. A Sage can also be termed by other names such as Rishi/Siddhar/Munivar/Seer etc. Sages in general are known to have made uncharted progress in fields such as Medicine, Science, Alchemy, Astronomy, Astrology, Manuscripts, Fine Arts like Literature, Music, Dance, Drama, Artistry, Sculpture etc. They have transcended across time & space and many of the Sages are said to have lived on the earthly realm across yugas spanning far upwards of more than 1000 years.

In the Tamil Siddha tradition, 18 sages are mentioned as prominent and are said to have lived during the times of the Gods dating way back to the time when the epics Ramayana & Mahabharatha were scripted. There are some minor differences with regard to the lists but sharing below the most prominent 18 Siddhars mentioned in scriptures

1) Agathiyar
2) Patanjali
3) Thirumoolar
4) Kamalamuni
5) Kudambai
6) Korakkar
7) Dhanvantri
8) Sundaranathar
9) Konganar
10) Sattaimuni
11) Valmiki
12) Ramadevar
13) Agapeyar
14) Idaikadhar
15) Machamuni
16) Karuvurar
17) Bhogar
18) Pambatti

Other than these 18 Siddhars, some lists tend to specify few other names of Siddhars by replacing a few from the above list. Some names missing from the above roster includes Kaga Bhujandar, Pulippani, Kalangi Nathar, Nandi Devar, Kanjamalai, Sennimalai, Punnakesar, Azhugunar, Theraiyar, Pulastya etc. Among the 18 Siddhars, Agathiyar is said to be the foremost figure of them all and considered as the Father of Siddha tradition.

18 Siddhars Birth Information
There are some additional information related to the above 18 Siddhars pertaining to the Nakshatra in operation when they were born, solar month at birth, their total life span and also the place of Jeeva Samadhi. Lets look at this information for all of the above sages.

1) Agathiyar (aka Agasthya)
Nakshatra at Birth: Ayilyam (Ashlesha)
Solar Month: Margazhi (Approx mid December to mid January)
Life Span: 4 Yugas & 48 Days
Jeeva Samadhi: Tiruvananthapuram
Information: Considered as the father of tamil literature and pioneer of Siddha medicine. Authored 'Agattiyam', an early Tamil Grammar treatise and Sanskrit works like Agastya Gita & Agastya Samhita.

2) Patanjali
Nakshatra at Birth: Moolam (Moola)
Solar Month: Panguni (Approx mid March to mid April)
Life Span: 5 Yugas & 7 Days
Jeeva Samadhi: Rameshwaram
Information: Authored many yogic texts including compilation of Yoga Sutra. Considered as an incarnation of Serpent Adishesha and made major strides in the field of Yoga.

3) Thirumoolar (aka Sundaranathar)
Nakshatra at Birth: Avittam (Dhanishta)
Solar Month: Purattasi (Approx mid September to mid October)
Life Span: 3000 Years & 13 Days
Jeeva Samadhi: Rameshwaram
Information: Author of “Thirumandiram” a spiritual classic merging yogic, philosophical, and Siddha principles. He is also considered as one of the 63 Nayanmars.

4) Kamalamuni
Nakshatra at Birth: Poosam (Pushya)
Solar Month: Vaigasi (Approx mid April to mid May)
Life Span: 4000 Years & 48 Days
Jeeva Samadhi: Thiruvarur
Information: Said to be a renowned disciple of Sage Thirumoolar. Known for spreading Siddha tradition widely

5) Kudambai
Nakshatra at Birth: Visagam (Vishakha)
Solar Month: Aadi (Approx mid July to mid August)
Life Span: 1800 Years & 16 Days
Jeeva Samadhi: Mayavaram
Information: Known for spiritual insights and Kundalini yoga. He was named as Kudambai (meaning a woman's ear ornament) due to his beauty

6) Korakkar (aka Gorakhnath)
Nakshatra at Birth: Ayilyam (Ashlesha)
Solar Month: Karthigai (Approx mid April to mid May)
Life Span: 880 Years & 11 Days
Jeeva Samadhi: Perur
Information: Known as a disciple of prominent sages such as Agasthya and Bhogar. Known for the art of telepathy and rejuvenation

7) Dhanvantri
Nakshatra at Birth: Punarpoosam (Punarvasu)
Solar Month: Aipasi (Approx mid October to mid November)
Life Span: 800 Years & 32 Days
Jeeva Samadhi: Vaitheeswaran Kovil
Information: Considered as the physician of the Gods and also an avatar of Lord Vishnu. Known for healing and medicinal properties

8) Sundaranandhar
Nakshatra at Birth: Revathi (Revathi)
Solar Month: Avani (Approx mid August to mid September)
Life Span: 800 Years & 28 Days
Jeeva Samadhi: Madurai
Information: Said to be a disciple of Sage Sattaimuni. It is said that he obtained the Siva Linga of Sage Agasthya, placed it at Saduragiri and worshipped it

9) Konganar
Nakshatra at Birth: Uthiradam (Uttara Ashada)
Solar Month: Chithirai (Approx mid April to mid May)
Life Span: 800 Years & 16 Days
Jeeva Samadhi: Thirupathi
Information: Said to be a disciple of Sage Bhogar. He mastered Siddha medicine and known for spiritual wisdom.

10) Sattaimuni
Nakshatra at Birth: Mrigaseerisham (Mrigashira)
Solar Month: Avani (Approx mid August to mid September)
Life Span: 800 Years & 14 Days
Jeeva Samadhi: Thiruvarangam
Information: Named as Sattaimuni (Sattai means shirt) because of a woolen shirt provided by Lord Shiva. Known for mastery in alchemy, astrology and medicine.

11) Valmiki (aka Vaalmeegar)
Nakshatra at Birth: Anusham (Anuradha)
Solar Month: Purattasi (Approx mid September to mid October)
Life Span: 700 Years & 32 Days
Jeeva Samadhi: Ettukudi
Information: Is revered as the Adi Kavi and is the author of one of the greatest epics "The Ramayana", Known for spiritual enlightenment and wisdom.

12) Ramadevar
Nakshatra at Birth: Pooram (Poorva Phalguni)
Solar Month: Maasi (Approx mid February to mid March)
Life Span: 700 Years & 6 Days
Jeeva Samadhi: Azhagarmalai
Information: Known as disciple of Sage Patanjali, made major initiations in the field of herbs and medicinal properties.

13) Agapeyar
Nakshatra at Birth: Mrigaseerisham (Mrigashira)
Solar Month: Panguni (Approx mid March to mid April)
Life Span: 700 Years
Jeeva Samadhi: Manavalanallur
Information: Known for using the mind as a ghost to guide people towards realisation. Is revered for his devotional songs on philosophy.

14) Idaikadhar
Nakshatra at Birth: Thiruvadirai (Arudra)
Solar Month: Purattasi (Approx mid September to mid October)
Life Span: 600 Years & 18 Days
Jeeva Samadhi: Thiruvannamalai
Information: Prominent for rearranging Navagrahas in order to stop a long time famine. Said to be an expert in astrology with his calculations being used in Panchangam

15) Machamuni (aka Matsyendranath)
Nakshatra at Birth: Rohini (Rohini)
Solar Month: Aadi (Approx mid July to mid August)
Life Span: 300 Years & 62 Days
Jeeva Samadhi: Thiruparankundram
Information: He is reckoned as the Fish Sage. Known for being a master of Kundalini awakening, meditation and Siddha medicine

16) Karuvurar
Nakshatra at Birth: Hastham (Hastha)
Solar Month: Chithirai (Approx mid April to mid May)
Life Span: 300 Years & 42 Days
Jeeva Samadhi: Karur
Information: Known as a disciple of Bhogar. Said to be a master alchemist and connected with herbal medicines

17) Bhogar
Nakshatra at Birth: Bharani (Bharani)
Solar Month: Vaigasi (Approx mid May to mid June)
Life Span: 300 Years & 18 Days
Jeeva Samadhi: Palani
Information: Responsible for installing the Navapashanam idol of Lord Muruga at Palani. Known widely for his works in China and said to be a pioneer in the field of medicine, yoga, spirituality.

18) Pambatti
Nakshatra at Birth: Mrigaseerisham (Mrigashira)
Solar Month: Karthigai (Approx mid April to mid May)
Life Span: 123 Years & 14 Days
Jeeva Samadhi: Shankaran Kovil
Information: Known as the snake charmer based on his name. He is widely known for his Kundalini energies and knowledge of various herbs and medicines.

From the above list, it is worth noting that only Sage Agasthya and Sage Patanjali's life span spreading across Yugas whereas all other Siddhar's life time spanning in the range from centuries to thousands of years. However the Sage who's believed to have the highest lifespan of all is Siddhar Kaga Bhujandar who is believed to have lived for millions of years across multiple cycles of creation and destruction. He is said to lived in the form of a crow and gets his name from 'Kagam' which translates as Crow in Tamil. He is termed as the "Immortal Sage" due to his perpetual timeline. Sage Kaga Bhujandar is believed to have given instructions to Sage Vasishta and obtained initiation from Lord Shiva in multiple eras.  

Nakshatra Connection of the Siddhars
Apart from these hallowed 18 Siddhars of the South, each of the 27 Nakshatras are also said to be associated with a Siddhar and in selective cases even 2 Siddhars. It is interesting to note that majority of these 18 fall as part of the Nakshatra list but since the Number of Nakshatras (27) are more than the prominent Siddhars of the South (supposedly 18), you will find few additional well respected Siddhars having born in particular Nakshatras and invoking them is said to be beneficial. Lets now look at all the Nakshatras and the Sages connected to them.

1) Ashwini - Kalangi Nathar
2) Bharani - Bhogar
3) Karthigai (Krithika) - Romarishi
4) Rohini - Machamuni (aka Matsyendranath)
5) Mrigaseerisham (Mrigashira) - Pambatti & Sattaimuni
6) Thiruvadirai (Arudra) - Idaikadhar
7) Punarpoosam (Punarvasu) - Dhanvantri
8) Poosam (Pushya) - Kamalamuni
9) Ayilyam (Ashlesha) - Agathiyar (aka Agasthya)
10) Magam (Magha) - Siva Vakiyar
11) Pooram (Poorva Phalguni) - Rama Devar (aka Yakobu)
12) Uthiram (Uttara Phalguni) - Kaga Bhujandar
13) Hastham (Hastha) - Karuvurar
14) Chithirai (Chitra) - Punakeesar
15) Swathi - Pulippani
16) Visagam (Vishakha) - Nandeeswarar (aka Nandi Devar) & Kudambai
17) Anusham (Anuradha) - Valmiki (aka Vaanmeekar)
18) Kettai (Jyeshta) - Vyasa
19) Moolam (Moola) - Patanjali
20) Pooradam (Poorva Ashada) - Rama Devar (aka Yakobu)
21) Uthiradam (Uttara Ashada) - Konganar
22) Thiruvonam (Shravana) - Dakshina Murthy
23) Avittam (Dhanishta) - Thirumoolar (aka Sundaranathar)
24) Sadayam (Shatabisha) - Kowbalar
25) Pooratathi (Poorva Bhadrapada) - Jyoti Muni
26) Uttirattathi (Uttara Bhadrapada) - Damaragar
27) Revathi - Sundara Nandhar

Thus, if one observes from the above list, each of the Nakshatra's are associated with at least one siddhar but in case of 2 of the Nakshatras viz Mrigaseerisham (Mrigashira) and Visagam (Vishakha), 2 Siddhars are casted along side them. Also for both Pooram (Poorva Phalguni) and Pooradam (Poorva Ashada) - the same Siddhar Rama Devar is provided for both. Though technically it has to be noted that Rama Devar also belongs as part of the 18 Siddhars and was said to have taken birth in Pooram (Poorva Phalguni) Nakshatra only. It could be that since Pooradam (Poorva Ashada) doesn't have a singular sage, Rama Devar is linked to it. The reason could also be that its the 10th Nakshatra from Pooram indicated as Karma Nakshatra as per the holy astrological text Kumaraswamiyam. Pooram also sometimes takes into account Sri Andal - the divine poet saint (Alwar) from Vishnu clan but however Andal cannot distinctively be equated to a Sage and hence may not be considered in this Sages list. Among the 18 Siddhars provided on top, some of them don't find their way in the Nakshatra list. For instance Korakkar Siddhar was born in Ayilyam (Ashlesha) but he is not linked directly to this star and only Agathiyar is linked. Similar is the case of Agapeyar Siddhar who also could technically be considered as a Sage to worship for Mrigaseerisham (Mriga) born natives.

Nakshatra relation to the Rishis
There is also believed to be a Nakshatra related with a particular Rishi. There are no repetitions here and each of the Nakshatras including Abhijit has one Rishi linked to its constellation. Thus praying to one's Rishi in relation to their birth star can be beneficial. This is most probably derived from Gothra or lineage of a Rishi connected to a particular Nakshatra. The names here are very different from the Nakshatras connected with Siddhars. In fact from the list of Siddhars, only Agasthya Munivar sees a mention in this list as well though he is connected to a different Nakshatra as per the lineage. Listing below the Rishis for all the 28 Nakshatras including the intercalary star of Abhijit.

1) Ashwini - Katyayana
2) Bharani - Rishibadhanya
3) Karthigai (Krithika) - Agnivesha
4) Rohini - Anurohi
5) Mrigaseerisham (Mrigashira) - Swethayi
6) Thiruvadirai (Arudra) - Bhargava
7) Punarpoosam (Punarvasu) - Vatsyayana
8) Poosam (Pushya) - Bharadwaja
9) Ayilyam (Ashlesha) - Jatukarna
10) Magam (Magha) - Vyaghrapada
11) Pooram (Poorva Phalguni) - Parashara
12) Uthiram (Uttara Phalguni) - Upashiva
13) Hastham (Hastha) - Mandavya
14) Chithirai (Chitra) - Gauthama
15) Swathi - Kaundinya
16) Visagam (Vishakha) - Kapi
17) Anusham (Anuradha) - Maitreya
18) Kettai (Jyeshta) - Kaushika
19) Moolam (Moola) - Kutsa
20) Pooradam (Poorva Ashada) - Haritha
21) Uthiradam (Uttara Ashada) - Kashyapa
22) Abhijit - Saunaka
23) Thiruvonam (Shravana) - Atri
24) Avittam (Dhanishta) - Garga
25) Sadayam (Shatabisha) - Dakshayana
26) Pooratathi (Poorva Bhadrapada) - Vatsa
27) Uttirattathi (Uttara Bhadrapada) - Agasthya
28) Revathi - Sankyayana

Siddhars associated with the Navagrahas
Other than the renowned 18 Siddhars, there is another list of 18 Siddhars representing the Navagrahas with each of the 9 planets being provided 2 Siddhars each. Lets take a look at the Siddhars for each planet.

Sun - Pattinathar, Kaduveli
Moon - Siva Vakiyar, Kambili
Mars - Bhogar, Pulippani
Mercury - Vallalar, Idaikadhar
Jupiter - Kaga Bhujandhar, Agapeyar
Venus - Kanjamalai, Sennimalai
Saturn - Kapilar, Karuvurar
Rahu - Alugunar, Pambatti
Ketu - Sattaimuni, Kudambai

Saptharishis
Apart from the 18 hallowed Siddhars from South, there is also a Rishi tradition termed as 'Saptharishis' known as the 7 divine sages of Hinduism. They are said to be seers embodying divine wisdom and cosmic order. The names of these Rishis keep changing across different cosmic cycles. As per the current age in existence, the 7 Rishis are listed as below:

- Atri
- Bharadwaja
- Gautama
- Jamadagni
- Kashyapa
- Vasishta
- Vishwamitra

A Manvantara is a cyclic period of time consisting of 71 Maha Yugas. There is said to be a total of 14 Manvantaras and currently the 7th Manvantara termed as Vaivasvata Manvantara is in operation. The first ever creation cycle known as the Svayambhuva Manvantara lists the Saptharishis as Atri, Angiras, Kratu, Marichi, Pulaha, Pulastya and Vasishta. Few other renowned Sages who have been part of Saptharishis as per different Manvantaras include Bhrigu, Kutsa, Gungu etc. There is also the name of Sage Agasthya in some lists of the Saptharishis.

Agasthya & Vasishta Connection
It is difficult to say who the most prominent Sage of the Saptharishis is in similar lines to Sage Agasthya's reverence among the 18 Siddhars. However it is to be noted that among the Saptharishis across most of the lists tend to have Maharishi Vasishta as probably the most notable Rishi. Incidentally Sage Agasthya and Sage Vasishta are also considered to be twin brothers as per Hindu Mythology having born from the semen of the deities Mitra and Varuna. There is also a reference in Yoga Vasishta that Sage Vasishta was born for the 8th time in this particular era. There is not much information on birth details of the Saptharishis as compared to the Siddhars but however it is believed that Rishi Vasishta was born in the lunar month of Vaisakh in Shukla Paksha Navami Tithi which is believed  to be the same Tithi as that of his disciple Lord Rama. Another revered Rishi connected closely to Vasishta viz Brahmarishi Vishwamitra is said to be have been born in the lunar month of Karthik during the waxing phase of the Moon in Tritiya Tithi.

Vasishta's Ancestral History and Linkage with Other Sages
The Puranas state Sage Vasishta to be one of the mind born sons of Lord Brahma. Vasishta along with his consort Arundathi are mentioned to have given birth to Maharishi Shakti who has been referred to in the epic Mahabharat. Sage Shakti subsequently gave birth to Maharishi Parashara who is well known as the author of many hindu texts and considered a father figure of Astrology having written the eternal classic "Brihat Parashara Hora Shastra". From Parashara, was born Maharishi Vyasa who is traditionally credited to being the author of the greatest epic "Mahabharat". From Vyasa was born Maharishi Sukar in the form of a parrot face who is recognised as the foremost narrator of the scripture "Bhagavata Purana".

Inset Left to Right: Lord Brahma -> Sage Vasishta -> Sage Shakti -> Sage Parashara -> Sage Vyasa -> Sage Sukar

Sanakadi Munis (Four Kumaras) and the Association with Lord Brahma & Guru Dakshinamurthy
Speaking of Lord Brahma and mind born sons, there are also 4 other mind born sons created by Brahma whose names are Sanaka, Sanandana, Sanatana and Sanat Kumara. They are commonly termed as the Four Kumaras and also known as Sanakadi Rishis. They are described as the first ever mind born creations and believed to have undertaken lifelong celibacy with their purpose being forever learning and being in the spiritual realm through devotional services with no desire whatsoever towards anything materialistic. In many iconographies, you would see these 4 Sages being under the tutelage of Lord Dakshinamurthy to seek the ultimate truth and get imparted with supreme knowledge.

Janma Nakshatra of the Saptharishis and the Great Bear Constellation
Unlike the 18 Siddhars of the South who are all associated with a specific Nakshatra in which they are born, there is no explicit mention of the Birth Nakshatra of the Saptharishis. There is however a connection with the constellation of Great Bear also known as Ursa Major forming 7 bright stars in the Sky known as the Big Dipper. Sage Vasishta is linked to the star of 'Mizar' and his consort Arundhati is connected to the nearby star of 'Alcor'. They are said to be double stars bonded together and is said to represent closeness, loyalty and harmony. In Hindu tradition, Vasishta & Arundhati are seen as a perfect couple from a marriage perspective embodying respect, devotion and marital bliss. The 7 star names as part of the Big Dipper comprise of Alkaid, Mizar, Alioth, Megrez, Phecda, Merak and Dubhe. Mizar & Alcor are said to be tied together. However it should be noted that these stars belonging as part of the Big Dipper do not exactly correspond to the Hinduism structure of 27 Nakshatras (or 28 inclusive of Abhijit).

Nakshatra Saptharishi Lineage
The only direct reference to Nakshatras is for one set of the Saptharishis where the 28 Nakshatras are assigned as 4 each among the Saptharishis. This is more in line with saying that one born in a particular Nakshatra will be coming under the lineage of that Rishi. Let's look at the list of the Nakshatras and the Kula Gothra Rishi associated with it. 

-> Ashwini, Poosam (Pushya), Swathi, Abhijit - Rishi Marici
-> Bharani, Ayilyam (Ashlesha), Visagam (Vishakha), Thiruvonam (Shravana) - Rishi Vasishta
-> Karthika (Krithika), Magam (Magha), Anusham (Anuradha), Avittam (Dhanishta) - Rishi Angiras
-> Rohini, Pooram (Poorva Phalguni), Kettai (Jyeshta), Sadayam (Satabisha) - Rishi Atri
-> Mrigaseerisham (Mrigashira), Uthiram (Uttara Phalguni), Moolam (Moola), Pooratathi (Poorva Bhadrapada) - Rishi Pulastya
-> Thiruvadirai (Arudra), Hastham (Hastha), Pooradam (Poorva Ashada), Uthirattathi (Uttara Bhadrapada) - Rishi Pulaha
-> Punarpoosam (Punarvasu), Chithirai (Chitra), Uthiradam (Uttara Ashada), Revathi - Rishi Kratu

Siddhar Mantra
There is also a Mantra which is beneficial to be chanted when worshipping the Siddhar of one's Janma Nakshatra. This needs to be done with devotion reverencing your respective Siddhar thinking of the task and reciting it for 48 days at a stretch for 108 times. The Mantra goes as follows consisting of the Bheeja Aksharam as "Om Sing Rang Ang Sing" / "ஓம் சிங் ரங் அங் சிங்"

Nakshatra Siddhar Information
Summarising list of all the 27 Nakshatras connected with the respective Siddhars along with images and information on their Jeeva Samadhi location.

Ashwini:
Siddhar: Kalangi Nathar
Jeeva Samadhi: Kanchamalai and Thirukadaiyur

Bharani:
Siddhar: Bhogar
Jeeva Samadhi: Pazhani

Karthigai (Krithika):
Siddhar: Romarishi
Jeeva Samadhi: No Samadhi, it is believed he directly ascended to Kailash. It is suggested to worship him on Mondays by being seated in North direction and offering sweet jaggery 

Rohini:
Siddhar: Machamuni (aka Matsyendranath)
Jeeva Samadhi: Thiruparankundram

Mrigaseerisham (Mrigashira)
Siddhar: Pambatti & Sattaimuni (aka Sattainathar)
Jeeva Samadhi: For Pambatti it is Sankaran Kovil and Sattaimuni it is Thiruvarangam

Thiruvadirai (Arudra)
Siddhar: Idaikadhar
Jeeva Samadhi: Thiruvannamalai

Punarpoosam (Punarvasu)
Siddhar: Dhanvantri
Jeeva Samadhi: Vaitheeswaran Kovil

Poosam (Pushya)
Siddhar: Kamalamuni
Jeeva Samadhi: Thiruvarur

Ayilyam (Ashlesha)
Siddhar: Agathiyar (aka Agasthya)
Jeeva Samadhi: Thiruvananthapuram. His glow of light (Oli Vattam) is said to be in Podhigai Mazhai at Kutralam

Magam (Magha)
Siddhar: Siva Vaakiyar 
Jeeva Samadhi: Kumbakonam

Pooram (Poorva Phalguni)
Siddhar: Ramadevar 
Jeeva Samadhi: Azhagar Malai. There is also a Samadhi believed to be in Mecca, Saudi Arabia

Uthiram (Uttara Phalguni)
Siddhar: Kaga Bhujandar 
Jeeva Samadhi: Uraiyur in Trichy District

Hastham (Hastha)
Siddhar: Karuvurar 
Jeeva Samadhi: Karur. His glow of light (Oli Vattam) is said to be in Periya Kovil at Thanjavur

Chithirai (Chitra)
Siddhar: Punnakeesar 
Jeeva Samadhi: Nannaser

Swathi
Siddhar: Pulippani
Jeeva Samadhi: Vaigavur near to Pazhani

Visagam (Vishakha)

Siddhar: Nandeesar (aka Nandi Devar) & Kudambai
Jeeva Samadhi: For Nandeesar it is Kasi Nagar and Kudambai it is Mayavaram

Anusham (Anuradha)
Siddhar: Valmiki aka Vaalmeegar 
Jeeva Samadhi: Ettukudi

Kettai (Jyeshta)
Siddhar: Vyasa 
Jeeva Samadhi: No Samadhi, it is believed that he dissolved all by himself. It is said that just thinking of him alone is enough and he will be there to support

Moolam (Moola)
Siddhar: Patanjali
Jeeva Samadhi: Rameshwaram

Pooradam (Poorva Ashada)

Siddhar: Ramadevar aka Yagopu
Jeeva Samadhi: Azhagar Malai. There is also a Samadhi believed to be in Mecca, Saudi Arabia

Uthiradam (Uttara Ashada)
Siddhar: Konganar 
Jeeva Samadhi: Tiruppathi

Thiruvonam (Shravana)
Siddhar: Dakshinamurthy
Jeeva Samadhi: Pallithennal near Pondicherry

Avittam (Dhanishta)
Siddhar: Thirumoolar
Jeeva Samadhi: Chidambaram

Sadayam (Satabhisha)

Siddhar: Kowbalar
Jeeva Samadhi: No information is available. However it is believed that just thinking of him will enable him to grant his grace

Pooratathi (Poorva Bhadrapada)
Siddhar: Jyoti Muni
Jeeva Samadhi: No Samadhi. It is believed that he took life in the form of Jyoti (Diya). Thus lighting lamps alone would invoke his grace

Uttirattathi (Uttara Bhadrapada)
Siddhar: Damaragar
Jeeva Samadhi: No Samadhi. It is believed that he directly dissolved himself. Legend states that he will do service for human race in the form of music

Revathi
Siddhar: Sundara Nandhar
Jeeva Samadhi: Madurai

Note: For Pooratathi (Poorva Bhadrapada) star, the Siddhar is Jyoti Muni who is said to have appeared in the form of a jyoti (light), hence there is no traditional Siddhar picture. Thus any invocation of the divine with the background of the light of Diya can be used as a methodology for Siddhar worship. For Uthirattathi (Uttara Bhadrapada) also, there is not much information available on Sage Damaragar hence the image may not be of the correct Siddhar. For this star it is suggested to pray to the Siddhar through the medium of bell sounds. However irrespective of the pictures, just thinking of one's respective Siddhar and praying to them will have the same effect and its not required to always only see an image and pray to them. A majority of the pictures in this article have been sourced from the web.

Navagraha Siddhar Information
Summarising list of all the 9 Navagrahas connected with the respective 2 Siddhars linked to each of the planets Sun, Moon, Mars, Mercury, Jupiter, Venus, Saturn, Rahu and Ketu.

Sun:
Siddhar: Pattinathar & Kaduveli

Moon:

Siddhar: Siva Vakiyar & Kambili

Mars:

Siddhar: Bhogar & Pulippani

Mercury:

Siddhar: Vallalar & Idaikadhar

Jupiter:

Siddhar: Kaga Bhujandar & Agapeyar

Venus:

Siddhar: Kanjamalai & Sennimalai

Saturn:

Siddhar: Kapilar & Karuvurar

Rahu:

Siddhar: Alugunar & Pambatti

Ketu:

Siddhar: Sattaimuni & Kudambai