A supporting actor performs roles in a play or movie other than that of protagonist. A female who performs these roles is usually referred to as a supporting actress.

These roles range from bit parts to secondary leads. They are sometimes but not necessarily character roles. A supporting actor must also use restraint not to upstage the main actor/actress in the play/movie. In earlier times these were often ethnic stereotypes. The title is usually specific to the performance, that is, a person may be a supporting actor in one film and the leading actor in the next. An individual who typically plays supporting roles is considered a character actor.

In television, a day player refers to most performers with supporting speaking roles hired on a daily basis without long-term contracts.