Rowan & Martin's Laugh-In (often simply referred to as Laugh-In) is an American sketch comedy television program that ran for 140 episodes from January 22, 1968, to March 12, 1973, on the NBC television network, hosted by comedians Dan Rowan and Dick Martin. It originally aired as a one-time special on September 9, 1967, and was such a success that it was brought back as a series, replacing The Man from U.N.C.L.E. on Mondays at 8 pm (ET). It quickly became the most popular television show in the United States.

The title of the show was a play on the 1960s hippie culture "love-ins" or the counterculture "be-ins", terms derived from the "sit-ins" common in protests associated with civil rights and antiwar demonstrations of the time. In 2002, Rowan & Martin's Laugh-In was ranked number 42 on TV Guide's 50 Greatest TV Shows of All Time. In the pilot episode, Dan Rowan explained the show's approach: "Good evening, ladies and gentlemen, and welcome to television's first Laugh-In. Now for the past few years, we have all been hearing an awful lot about the various 'ins'. There have been be-ins, love-ins, and sleep-ins. This is a laugh-in and a laugh-in is a frame of mind. For the next hour, we would just like you to sit back and laugh and forget about the other ins." The good-natured, lighthearted, and informal disposition of the show was thereby established.

Laugh-In had its roots in the humor of vaudeville and burlesque, but its most direct influences were Olsen and Johnson's comedies (such as the free-form Broadway revue Hellzapoppin'), the innovative television works of Ernie Kovacs, and the topical TV satire That Was the Week That Was. The show was characterized by a rapid-fire series of gags and sketches, many of which were politically charged or contained sexual innuendo. The co-hosts continued the exasperated straight man (Rowan) and "dumb guy" (Martin) act which they had established as nightclub comics. The show featured Gary Owens as the on-screen announcer, and an ensemble cast; Ruth Buzzi was part of the ensemble throughout the show's six year run, while others who appeared in at least three seasons included Judy Carne, Henry Gibson, Goldie Hawn, Arte Johnson, Jo Anne Worley, Alan Sues, Lily Tomlin, Dennis Allen and Richard Dawson.