Soap is an American sitcom television series that originally ran on ABC from September 13, 1977, until April 20, 1981. The show was created as a nighttime parody of daytime soap operas, presented as a weekly half-hour prime time comedy. Similar to a soap opera, the show's story was presented in a serial format, and featured melodramatic plotlines including alien abduction, demonic possession, extramarital affairs, murder, kidnapping, unknown diseases, amnesia, cults, organized crime, a communist revolution, and teacher-student relationships. In 2007, it was listed as one of Time magazine's "100 Best TV Shows of All-Time", and in 2010, the Tates and the Campbells ranked at number 17 in TV Guide's list of "TV's Top Families".

The show was created, written, and produced by Susan Harris, and also executive produced by Paul Junger Witt and Tony Thomas. Each returning season was preceded by a 90-minute retrospective of the previous season. Two of these retrospectives were made available on VHS in 1994, but were not included on any DVD collections.

The show aired 85 episodes over the course of four seasons. Of these, eight episodes (including the final four) aired as one-hour episodes during the original run on ABC. These hour-long episodes were later split in two, yielding 93 half-hour episodes for syndication. Like most sitcoms of the era, Soap was videotaped rather than filmed, but this helped further its emulation of the daytime soap opera format, as most such productions were also videotaped. All episodes are available on Region 1 DVD in four box sets. There is a box set of Season 1 on Region 2 DVD. The series has rerun in syndication on local channels as well as on cable.

The show starred Katherine Helmond and Cathryn Damon as sisters and matriarchs of their own families. The cast also included several former soap opera actors. Robert Mandan (Chester Tate) had previously appeared on Search for Tomorrow as a leading man for Mary Stuart; Donnelly Rhodes (Dutch Leitner) had played the first husband of Katherine Chancellor on The Young and the Restless; Arthur Peterson Jr. ("The Major") played Rev. John Ruthledge in the radio version of Guiding Light, while Caroline McWilliams appeared on the television version as Janet Mason Norris; and Marla Pennington (Leslie Walker) appeared for three years as Samantha Livingston Chandler on General Hospital. Additionally, after the series ended, Lynne Moody (Polly Dawson) went in to appear in a recurring capacity on primetime soap opera Knots Landing (which also starred Ted Shackelford, who appeared on Soap in a guest appearance), and Roscoe Lee Browne appeared in a recurring guest role in the seventh season of Falcon Crest.