The term guest appearance generally denotes the appearance of a guest in an artistic or pop-culture setting.

The guests themselves (referred to as guest artists, featured artists, guest stars, or guest fighters, depending on context), are distinguished from the other real artists or fictional characters by not being part of or fitting the usual theme of the cast. They are usually recognisable on their own and only appear once or rarely within that cast.

In show business, a guest appearance is the participation of an outsider performer (such as a musician or actor) in an event such as a music record or concert, show, etc., when the performer does not belong to the regular band, cast, or other performing group. In music, such an outside performer is often referred to as a guest artist.

Guest appearances have been known in theatre, ballet, and classical music for centuries, with guests both from the home country and from abroad. The advent of air transport has made this practice much more practical and global.

In classical music, guest orchestra conductors are a common practice.

Guest artists should not be confused with touring groups, troupes, orchestra, or even individual artists, although the distinction may be blurred. In the case of touring, their act is independent in itself, while the guest takes part in the act of the resident staff.

The duration of involvement of a guest artist may vary, from separate short-term acts with fees per concert to fixed temporary contracts for several seasons.

In the early days of the pop music industry the bands were relatively stable units, and while guests were not uncommon, they were seldom given credits on album covers. For example, Eric Clapton was not credited in print for his guitar performance in the release of "While My Guitar Gently Weeps" of The Beatles. Gradually guest appearances have become a fully credited staple of music industry. The custom of guest appearance has become especially prominent in rap music, and this influenced rock musicians as well.