R. Ranganathan (7 October 1938 – 27 July 2016), known professionally as Gnanakoothan, was an Indian poet.
Writing in Tamil, he was the author of Anru veru kizhamai ("That was another day"), Suriyanukku Pinpakkam ("The rear side of Sun"), Kadarkaraiyil Sila Marankal ("Few trees in the seashore"), Meendum Avarkal ("Them again"), and Pencil Padangal ("Pencil pictures").
His works also appeared in little magazines like Illakkiya Vattam of Ka.
[4] He entered the field of poetry through the poem Prachanai (The problem).
Antru Veru Kilamai, Sooriyanukku pinpakkam, Kadarkariyil Sila Marangal and Meendum Avargal are his famous works.