Infinite Jest is a 1996 novel by American writer David Foster Wallace. Categorized as an encyclopedic novel, Infinite Jest is featured in Time magazine's list of the 100 best English-language novels published between 1923 and 2005.

The novel has an unconventional narrative structure and includes hundreds of extensive endnotes, some with footnotes of their own.

A literary fiction bestseller after having sold 44,000 hardcover copies in its first year of publication, the novel has since sold more than a million copies worldwide.

Wallace began Infinite Jest, "or something like it", several times between 1986 and 1989. His efforts in 1991–92 were more productive; by the end of 1993, he had a working draft of the novel.

From early 1992 until the novel's publication, excerpts from various drafts appeared sporadically in magazines and literary journals including Harvard Review, Grand Street, Conjunctions, Review of Contemporary Fiction, Harper's Magazine, The Iowa Review, The New Yorker and the Los Angeles Times Magazine.

The book was edited by Michael Pietsch of Little, Brown and Company. Pietsch made suggestions and recommendations to Wallace, but every editing decision was Wallace's. He accepted cuts amounting to around 250 manuscript pages from his original submission. He resisted many changes for reasons that he usually explained.

The novel gets its name from Hamlet, Act V, Scene 1, in which Hamlet holds the skull of the court jester, Yorick, and says, "Alas, poor Yorick! I knew him, Horatio: a fellow of infinite jest, of most excellent fancy: he hath borne me on his back a thousand times; and now, how abhorred in my imagination it is!"

Wallace's working title for Infinite Jest was A Failed Entertainment.