What's My Line? is a panel game show that originally ran in the United States, between 1950 and 1967, on CBS. The game show started in black and white and later in color, with subsequent U.S. revivals. The game uses celebrity panelists to question contestants in order to determine their occupation. The majority of the contestants were from the general public, but there was one weekly celebrity "mystery guest" for which the panelists were blindfolded. It is on the list of longest-running U.S. primetime network television game-shows. Originally moderated by John Charles Daly and most frequently with regular panelists Dorothy Kilgallen, Arlene Francis, and Bennett Cerf, What's My Line? won three Emmy Awards for "Best Quiz or Audience Participation Show" in 1952, 1953, and 1958 and the Golden Globe Awards for Best TV Show in 1962.

A panel show or panel game is a radio or television game show in which a panel of celebrities participate. Celebrity panelists may compete with each other, such as on The News Quiz; facilitate play by non-celebrity contestants, such as on Match Game and Blankety Blank; or do both, such as on Wait Wait Don't Tell Me. The genre can be traced to 1938, when Information Please debuted on U.S. radio. The earliest known television panel show is Play the Game, a charades show in 1946. The modern trend of comedy panel shows can find early roots with Stop Me If You've Heard This One in 1939 and Can You Top This? in 1940. While panel shows were more popular in the past in the U.S., they are still very common in the United Kingdom.