In show business (music, TV shows, etc.), a guest appearance is a participation of an outsider performer (musician, actor, etc.), usually called guest artist (guest dancer, guest violinist, etc.), in an event (music record, concert, show, etc.), i.e., the participation of a performer which does not belong to the regular crew (cast, band, contract personnel, etc.)"The Dance Encyclopedia" by Anatole Chujoy, Phyllis Winifred Manchester, 1967, Simon and Schuster, p. 434, article "Guest Artist" In performance art, the terms guest role or guest star are also common, the latter term specifically indicating the guest appearance of a celebrity. The latter is often also credited as "Special guest star" or "Special Musical Guest Star"Special guest and Special Musical Guest credits were the practice on the Charmed television series. by some production companies.

In pop music guest appearances are often described with the words featuring, featured, etc., and abbreviated in credit lists as Feat., Ft., f.

In television series, a guest star is an actor who appears in one or a few episodes. In radio and television shows, a guest star is a guest of the show who is a celebrity.