Underworld is a novel published in 1997 by Don DeLillo. It was nominated for the National Book Award, was a best-seller, and is one of DeLillo's better-known novels.

In 2006, a survey of eminent authors and critics conducted by The New York Times found Underworld the runner-up for the best work of American fiction of the past 25 years; it garnered 11 of 125 votes, finishing behind only Toni Morrison's Beloved with 15 votes