"Lithium" is a song by the American rock band Nirvana, written by vocalist and guitarist, Kurt Cobain. It appears as the fifth track on the band's second album Nevermind, released by DGC Records in September 1991.

In a 1992 interview with California fanzine Flipside, Cobain explained that the song was a fictionalized account of a man who "turned to religion as a last resort to keep himself alive" after the death of his girlfriend, "to keep him from suicide." Nirvana biographer Michael Azerrad described its lyrics as "an update on Marx's description of religion as the 'opiate of the masses.'"

"Lithium" was released as the third single from Nevermind in July 1992, peaking at number 64 on the US Billboard Hot 100 and number 11 on the UK Singles Chart. It also reached number one in Finland and the top five in Ireland and Portugal. The accompanying music video, directed by American filmmaker Kevin Kerslake, is a compilation of live footage from the band's October 31, 1991, concert at the Paramount Theatre in Seattle, Washington, and from the completed but then-unreleased film, 1991: The Year Punk Broke.