Lead Role
1. plays the role of the protagonist in a film or play. The word lead may also refer to the largest role in the piece and leading actor may refer to a person who typically plays such parts or an actor with a respected body of work. Some actors are typecast as leads, but most play the lead in some performances and supporting or character roles in others.
Sometimes there is more than one significant leading role in a dramatic piece, and the actors are said to play co-leads; a large supporting role may be considered a secondary lead.