Underworld is a 1997 novel by the American writer Don DeLillo. The novel is centered on the efforts of Nick Shay, a waste management executive who grew up in the Bronx, to trace the history of the baseball struck in The Shot Heard 'Round the World, and encompasses numerous subplots drawn from American history in the second half of the twentieth century. Described as both postmodernist and a reaction to postmodernism, it examines themes of nuclear proliferation, waste, and the contribution of individual lives to the course of history.
A best-seller that was nominated for the National Book Award and shortlisted for the Pulitzer Prize, Underworld is often regarded as DeLillo's supreme achievement. In 2006, a survey of eminent authors and critics conducted by The New York Times named Underworld as the runner-up for the best work of American fiction of the past 25 years, behind only Toni Morrison's Beloved.