The Second City is a long-running improvisational comedy troupe based in the Old Town area of Chicago, Illinois, with offshoot troupes in other cities, most notably Toronto.

Second City evolved from the Compass Players, a 1950s cabaret-style revue show. The troupe chose the self-mocking name "Second City" from the title of a disdainful article about Chicago by A.J. Liebling that appeared in The New Yorker magazine in 1949. In 1959 the first Second City revue show premiered. The style of comedy has changed with the times, but the format has remained constant. Second City revues feature a mix of semi-improvised and scripted scenes (known as blackouts). New material is developed during unscripted improv sessions, where scenes are created based on audience suggestions. A Second City innovation is the inclusion of live, improvised music in the performance.

A number of important performers got their start here, and later moved on to television and movie careers. In the late 1970s Second City Chicago became a source of players for the Saturday Night Live television show, which borrowed many of the writing and performing techniques pioneered by Second City and other improv groups. Shortly thereafter members of the Toronto troupe created the "SCTV" television show.

Notable alumni of the Chicago Second City troupe

• Alan Arkin
• James Belushi
• John Belushi
• Peter Boyle
• Dan Castellaneta
• Stephen Colbert
• Chris Farley
• Tina Fey
• Bonnie Hunt
• Robert Klein
• Shelley Long
• Bill Murray
• Joan Rivers
• Amy Sedaris
• Fred Willard

Notable alumni of the Toronto Second City troupe

• Dan Aykroyd
• John Candy
• Eugene Levy
• Andrea Martin
• Colin Mochrie
• Mike Myers
• Catherine O'Hara
• Gilda Radner
• Harold Ramis
• Martin Short
• Dave Thomas

Notable alumni of the Cleveland Second City troupe

• Jack Hourigan

Notable alumni of the Compass Players

• Mike Nichols and Elaine May
• Alan Alda
• Ed Asner
• Jerry Stiller and Anne Meara
• Shelley Berman