American sketch comedy and variety television series that has aired on Saturday nights on the National Broadcasting Company (National Broadcasting Co., Inc.) (NBC) network since 1975, becoming one of the longest-running programs in television. The series is a fixture of NBC programming and a landmark in American television.

NBC developed Saturday Night Live as an edgy comedy series designed to appeal to viewers ages 18 to 34, and, notwithstanding a few slumps, the show has consistently attracted new viewers who have entered that demographic group while remaining a favourite with many who have moved out of it. The 90-minute program was created by Dick Ebersol and Lorne Michaels, the latter of whom continues as a writer and executive producer of the show, after having taken a brief hiatus in the early 1980s. Each episode features the show's regular ensemble of comedic actors, as well as a guest host and a musical guest. The show always begins with an opening sketch that ends with the signature phrase, “Live from New York, it's Saturday Night!” Filming before a studio audience and broadcasting live (with Western time zones viewing a tape delay) has given the show its without-a-net edge and has led to many memorable moments, as well as a few controversies and missteps (perhaps most notably, in 1992, Irish singer Sinéad O'Connor ripping up a photograph of Pope John Paul II on camera, prompting an outraged response from thousands of viewers).

Mixing topical and political subject matter with observational humour and parody, SNL borrowed elements from the format of British television's pioneering That Was the Week That Was (1962–63, hosted by David Frost). But beyond those roots, from its inception it has been firmly grounded in the form of improvisational comedy developed in Chicago in the 1950s and '60s by the Compass Players and at Second City. Indeed, Second City (both its original Chicago and its Toronto companies) and the Los Angeles improvisation group the Groundlings provided many of the performers who have made up SNL's ensemble, beginning with its original cast, known as the Not Ready for Primetime Players—Dan Aykroyd, John Belushi, Chevy Chase, Jane Curtin, Garrett Morris, Laraine Newman, and Gilda Radner. (This improvisation tradition also gave rise to Second City TV, which appeared first on Canadian television 【1976–80】 and then on NBC 【1981–83】, to the American Broadcasting Company's Fridays 【1980–82】, and to the Fox network's In Living Color 【1990–94】 and Mad TV 【1995– 】, among other programs.) Similarly, the brilliantly warped satire of National Lampoon magazine (and the National Lampoon Radio Hour 【1973–74】) was another important building block of SNL's irreverent comic sensibility.

The show's changing ensemble has been the launching pad for countless performers who have become major television and motion picture stars, most of them developing recurring signature characters or impersonations on SNL. The following list only scratches the surface of those who have made their name on the show: Bill Murray (Murray, Bill), Al Franken, Don Novello (“Father Guido Sarducci”), Eddie Murphy (Murphy, Eddie), Julia Louis-Dreyfus, Billy Crystal, Robert Downey, Jr., Dennis Miller, Dana Carvey, Phil Hartman, Chris Rock, David Spade, Chris Farley, Sarah Silverman, Mike Meyers, Adam Sandler, Molly Shannon, Will Ferrell, and Tina Fey (Fey, Tina). The anchor chair of SNL's fake news segment, Weekend Update, holds special prominence and has been notably occupied by Chase, Curtin, Akroyd, Murray, Miller, Norm MacDonald, and Fey, among others. The guest hosts tend to be celebrities on the rise or actors, including former cast members, with a new movie to publicize. There are a number of performers who have long been associated with SNL as guest hosts, including Steve Martin (Martin, Steve), Paul Simon (Simon, Paul), John Goodman (Goodman, John), Christopher Walken, and Alec Baldwin. From its start, the program also has been an essential gig for musicians, both for up-and-coming groups and singers as well as for some of the biggest names in the music industry, an eclectic array that has included Elvis Costello (Costello, Elvis), Nirvana, the Rolling Stones (Rolling Stones, the), Radiohead, Run-D.M.C., U2, and Britney Spears (Spears, Britney).