A character actor is a supporting actor who plays unusual, interesting, or eccentric characters. The term, often contrasted with that of leading actor, is somewhat abstract and open to interpretation. In a literal sense, all actors can be considered character actors since they all play "characters," but in the usual sense it is an actor who plays a distinctive and important supporting role.

In fiction, a character is a person or other being in a narrative. The character may be entirely fictional or based on a real-life person, in which case the distinction of a "fictional" versus "real" character may be made. Derived from the Ancient Greek word χαρακτήρ, the English word dates from the Restoration, although it became widely used after its appearance in Tom Jones by Henry Fielding in 1749. From this, the sense of "a part played by an actor" developed. Character, particularly when enacted by an actor in the theater or cinema, involves "the illusion of being a human person". In literature, characters guide readers through their stories, helping them to understand plots and ponder themes. Since the end of the 18th century, the phrase "in character" has been used to describe an effective impersonation by an actor. Since the 19th century, the art of creating characters, as practiced by actors or writers, has been called characterization.