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").
He was one of the modern Tamil poet in Tamil literature, and a regular contributor to topical columns in Tamil periodicals such as Kalki, Kalachuvadu and Uyirmai.
He was one of the founder-editors of the little magazine Kacatathapara along with N.
Krishnamurthy, Sa.
Kandasamy, and N.
Muthusamy.
He started and ran Gavanam for a brief period.
He was also one of the editors of Zha, along with Atmanam and R.
Rajagopalan.
He contributed to several little magazines including Maiyam, Vrutcham (now Naveena Vrutcham), and Kanaiyazhi.
His works also appeared in little magazines like Illakkiya Vattam of Ka.