An actor (or in some cases actress for females;  is a person who portrays a character in a performance. The actor performs "in the flesh" in the traditional medium of the theatre, or in modern mediums such as film, radio, and television.

The analogous Greek term is ὑποκριτής (hupokritḗs), literally "one who answers". The actor's interpretation of their role pertains to the role played, whether based on a real person or fictional character. Interpretation occurs even when the actor is "playing themselves", as in some forms of experimental performance art, or, more commonly; to act, is to create, a character in performance.

Formerly, in some societies, only men could become actors, and women's roles were generally played by men or boys.

When used for the stage, women occasionally played the roles of prepubescent boys