guest-star

/G S T S T AA1 R/
noun
  1. 1

    An actor on a TV programme who stars in one, or a few, episodes.

  2. 2

    A guest on a recording

verb
  1. 1

    (of an actor) to star as a guest.

  2. 2

    (of a player) to play as a guest of another team.

Source: https://en.wiktionary.org/wiki/guest%20star, https://en.wiktionary.org/wiki/guest-star