A. Sethumadhavan (born 5 June 1942), popularly known as Sethu, is a Malayalam fiction writer. He has published more than 30 books. He won the Kendra Sahitya Akademi Award in 2007 for the work Adayalangal. He received the Kerala Sahitya Akademi Awards in 1982 and 1978 for his works Pandavapuram and Pediswapnangal; and Vayalar Award for Adyalangal in 2005. Sethu's 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.