Nimrod is the fifth studio album by American rock band Green Day, released on October 14, 1997, by Reprise Records. The band began work on the album in the wake of the cancellation of a European tour after the release of their previous album, Insomniac. Recorded at Conway Recording Studios in Los Angeles, the album was written with the intent of creating a set of standalone songs as opposed to a cohesive album. Retrospectively, Nimrod is noted for its musical diversity and experimentation, containing elements of folk, hardcore, surf rock, and ska. Lyrical themes discussed include maturity, personal reflection, and fatherhood.

The album peaked at number ten on the Billboard U.S. charts and was certified double platinum by the Recording Industry Association of America (RIAA). The record was also certified triple platinum in Australia and double platinum in Canada. Upon release, Nimrod received generally positive reviews from critics, who praised Armstrong's songwriting. The album yielded the acoustic single "Good Riddance (Time of Your Life)", which appeared in numerous popular culture events, including the penultimate episode of the sitcom Seinfeld. To promote the album, Green Day embarked on an extensive touring schedule. The album was also reissued on vinyl on June 16, 2009, as well as for anniversary and deluxe edition releases in 2012, 2017, and 2023. The songs "Nice Guys Finish Last", "Hitchin' a Ride", and "Good Riddance (Time of Your Life)" are featured in the video game Green Day: Rock Band.