Kenneth Elton "Ken" Kesey (/ˈkiːziː/; September 17, 1935 – November 10, 2001) was an American novelist, essayist, and countercultural figure. He considered himself a link between the Beat Generation of the 1950s and the hippies of the 1960s.

Kesey was born in La Junta, Colorado and grew up in Springfield, Oregon, graduating from the University of Oregon in 1957. He began writing One Flew Over the Cuckoo's Nest in 1960 following the completion of a graduate fellowship in creative writing at Stanford University; the novel was an immediate commercial and critical success when published two years later. Subsequently, he moved to nearby La Honda, California and began hosting happenings with former colleagues from Stanford, miscellaneous bohemian & literary figures (most notably Neal Cassady), and other friends under the imprimateur of the Merry Pranksters; these parties, known as Acid Tests, integrated the consumption of LSD with multimedia performances. He mentored the Grateful Dead (the de facto "house band" of the Acid Tests) throughout their incipience and continued to exert a profound influence upon the group throughout their long career. Sometimes a Great Notion—an epic account of the vicissitudes of an Oregon logging family that aspired to the modernist grandeur of William Faulkner's Yoknapatawpha saga—was a commercial success that polarized critics and readers upon its release in 1964, although Kesey regarded the novel as his magnum opus.