S. Rangarajan better known by his allonym Sujatha, was an Indian author, novelist and screenwriter who wrote in Tamil. He authored over 100 novels, 250 short stories, ten books on science, ten stage plays, and a slim volume of poems. He was one of the most popular authors in Tamil literature, and a regular contributor to topical columns in Tamil periodicals such as Ananda Vikatan, Kumudam and Kalki. He had a wide readership, and served for a brief period as the editor of Kumudam, and has also written screenplays and dialogues for several Tamil films.