Saathanaar or Seethalai Saathanaar (Tamil: சாத்தனார் or சீத்தலைச் சாத்தனார், cītalai cāttanār) was the Tamil poet who composed the epic Manimekalai. A total of 11 verses of the Sangam literature have been attributed to Saathanaar, including verse 10 of the Tiruvalluva Maalai.

Pronounced Saa-tha-naar, the name is derived from (Tamil: சாத்து, sāttu) meaning Buddhist monk. Applying this principle to the name Maturai Kulavāṇikan Cāttan, the author of Manimekalai, we see that the two appellations Madhurai and Kulavanikan were prefixed to his name in order to distinguish him from another poet of Madhurai with the same name and from a third who lived elsewhere.

Saathanaar hailed from a place known as Seerthandalai, later came to be known as Seethalai. He was a grain merchant at Madhurai and hence came to be called "Koolavanigan". He was a contemporary of Cheran Senguttuvan and was believed to have practiced Buddhism. He has sung in praise of the Pandyan king Chittira Maadatthu Thunjiya Nanmaran in the Sangam work of Purananuru.

Vaiyapuri Pillai sees him along with Ilango Adigal as developing two divergent strands of the Silampu legend that forms the basis for both Silapatikaram and Manimekalai. He is seen as an expert in both orthodox and heterodox systems of Indian philosophy and as an advocate of Buddhist philosophy. It is seen that Maṇimekalai was written after the Tirukkural was composed, because there are two verses from the Tirukkural quoted in Manimekalai.