Hollywood Squares (originally The Hollywood Squares, later stylized as H2: Hollywood Squares) is an American game show in which two contestants compete in a game of tic-tac-toe to win cash and prizes. The show originally aired as a pilot on NBC in 1965, and debuted on NBC as a regular series in October 1966. The board for the game is a 3 × 3 vertical stack of open-faced cubes, each occupied by a celebrity seated at a desk facing the contestants. The stars are asked questions by the host and the contestants judge the truth of their answers to gain squares in the right pattern to win the game.

Though Hollywood Squares was a legitimate game show, the game largely acted as the background for the show's comedy in the form of joke answers (commonly called "zingers" by the production staff), often given by the stars prior to their real answer. The show's writers usually supplied the jokes. In addition, the stars were given the questions' subjects and bluffs prior to the show. The show was scripted in this sense, but the gameplay was not. The original host Peter Marshall explained at the beginning of the Secret Square game, "the celebrities were briefed before the show to help them with bluff answers, but they are hearing the actual questions for the first time."

Marshall hosted the original version of Hollywood Squares that aired on NBC from 1966 to 1980, as well as a nighttime syndicated version that ran from 1971 to 1981. It then returned to NBC in 1983 as part of a 60-minute hybrid series with Match Game, featuring Jon Bauman hosting the Hollywood Squares portion of that show. Following Marshall's retirement, the show has since been revived twice in syndication: a version hosted by John Davidson from 1986 to 1989, and another hosted by Tom Bergeron from 1998 to 2004. Three revivals were run in the 2010s with a different title all on Paramount cable channels; in 2012, Hip Hop Squares on MTV2 with Peter Rosenberg, and from 2017 to 2019 on VH1 with DeRay Davis, in 2019, Nashville Squares on CMT with Bob Saget, and in 2023, Celebrity Squares on VH1 with John "DC Young Fly" Whitfield.

In 2013, TV Guide ranked it at No. 7 in its list of the 60 greatest game shows ever. Internationally, there have been multiple versions produced under a variety of names (see International versions below). When combined with two spinoffs of the franchise, the show has been produced for seven different decades.

In May 2024, it was announced that the show would be revived by CBS (which has owned the rights to the program since 2000, when it acquired format owner King World), with Drew Barrymore as a co-executive producer and center square, and Nate Burleson as host. The series premiered on January 16, 2025. On February 24, 2025, the revival was renewed for a second season.