General:
* Player: This was a common term in Shakespeare's time, and is still used today in phrases like "a player in the game."
* Histrion: This word carries a slightly more formal and old-fashioned tone.
* Thespian: This refers specifically to a dramatic actor, and comes from the name of the Greek playwright Thespis, who is credited with being the first actor.
More specific:
* Mimic: This word emphasizes the imitative nature of acting.
* Comedian: This refers to an actor who specializes in comedy.
* Tragediant: This refers to an actor who specializes in tragedy.
The best word to use will depend on the context and the specific meaning you want to convey.