Mark Leyner is an American postmodernist author.

Leyner employs an intense and unconventional style in his works of fiction. His stories are generally humorous and absurd: In The Tetherballs of Bougainville, Marks father survives a lethal injection at the hands of the New Jersey penal system, and so is freed but must live the remainder of his life in fear of being executed, at New Jerseys discretion, in any situation and regardless of collateral damage. They frequently incorporate elements of meta-fiction: In the same novel, an adolescent Mark produces a film adaptation of the story of his fathers failed execution, although he reads a newspaper review of the movie to the prisons warden, and then dies, before even leaving the prison. At the sentence level, Leyner uses sprawling imagery and an extravagant vocabulary, bordering on prose poetry.

Leyner has also worked as a columnist for Esquire and George magazines, and as a writer for the MTV program Liquid Television. He also co-wrote and voiced a short-lived series of audio fiction called Wiretap.

Leyner is most famously critiqued in David Foster Wallaces essay E Unibus Pluram: Television and U.S. Fiction. Despite this and appearances on David Letterman, Leyner remains a cult figure, though this may change as he switches over to the higher profile world of television development. (He has not written any novels for quite some time, presumably in order to devote more time to this new medium.)

Recently Leyner has collaborated with Dr. Billy Goldberg on three humorous, though fact-based, books on medicine.

He is credited with co-authoring the screenplay of War, Inc.