Sethumadhavan, popularly known as Sethu, is a Malayalam fiction writer. Sethu authored more than 30 books, won the Kendra Sahitya Akademi Award in 2007 for his work, Adayalangal. He also received the Kerala Sahitya Akademi Award in 1982 and 1978 for his works Pandavapuram and Pediswapnangal and Vayalar Award for Adayalangal in 2005. Sethu won the Odakkuzhal award for his novel Marupiravi. His other literary works include Velutha Koodarangal, Thaliyola, Kiratham, Niyogam, Sethuvinte Kathakal and Kaimudrakal. He also served as the chairman and CEO of the South Indian Bank.
He is one of the pioneers of modern Malayalam fiction who brought a radical transformation of sensibility through his writings during the sixties and early seventies. Many of his novels and stories have been translated into other Indian and foreign languages. Four of his works have been made into films including the much acclaimed Pandavapuram, which was also made into Bengali titled Nirakar Chhaya.