Devadevan (pen name of P. Kaivalliam, born 5 May 1948) is an eminent Tamil poet, writer, and literary thinker from Thoothukudi (Tuticorin), Tamil Nadu. Writing since the 1970s, he has published 123 poetry collections, making him one of the most prolific voices in contemporary Tamil poetry. His body of work also includes a book on poetic dialogue, a play, a short story collection, essays, speeches, and Religion of Poetry.

A founding president of the Darsana Film Society in Thoothukudi, Devadevan participated in the All India Poets' Seminar at Bharat Bhavan, Bhopal, in 1990. His contributions to Tamil literature have been widely recognized through numerous awards, a documentary on his poetry, and the critical study Tamil Poetry of Modernism with Devadevan as the Focal Point by noted writer and critic Jeyamohan. He currently lives in Bengaluru with his family.