Diane Chambers is a fictional character in the American television situation comedy show Cheers, portrayed by Shelley Long and created by Glen and Les Charles. After her fiancé Sumner Sloan abandons her in the Cheers bar in the pilot episode, Diane works as a bar waitress. She has an on-off relationship with the womanizing bartender Sam Malone and a one-year relationship with Frasier Crane, who later becomes a main character of the series and Frasier. When Long left the series during the fifth season, the producers wrote her character out. After that, they added her permanent replacement Rebecca Howe, a businesswoman played by Kirstie Alley, in the sixth season. Shelley Long made a special guest appearance as Diane in the series finale, as well as in Frasier as a one-time figment of Frasier's imagination, and as the actual Diane in the crossover episode "The Show Where Diane Comes Back".

Cheers is an American sitcom television series that aired on NBC from September 30, 1982, to May 20, 1993, with a total of 275 episodes across eleven seasons. The show was produced by Charles/Burrows/Charles Productions in association with Paramount Network Television and was created by the team of James Burrows and Glen and Les Charles. The show is set in the titular bar in Boston, where a group of locals meet to drink, relax, socialize, and escape from their day to day issues.