Cameo appearance

A cameo role or cameo appearance (often shortened to just cameo) is a brief appearance of a known person in a work of the performing arts, such as plays, movies, video games and television. Such a role does not have to be an actor: short appearances by movie directors, politicians, athletes, and other celebrities are common.

Some examples would be Alfred Hitchcock briefly appearing in some of his movies or Stan Lee always briefly appearing in Marvel-related movies or Salman Khan's apperance in Pathaan.