Sujatha was the allonym of the Tamil author S. Rangarajan, Author of 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 movies.

As an engineer, he supervised the design and production of the electronic voting machine (EVM) during his tenure at Bharat Electronics Limited (BEL), a machine which is currently used in elections throughout India. As an author he inspired many authors, including Balakumaran, Madhan.