noun
co-star; co-performer
Refers to someone who performs together with another person in a show, film, play, or other performance.
彼は新しい映画で有名な俳優と共演者になった。
He became a co-star with a famous actor in the new movie.
舞台で共演者との息がぴったり合った。
On stage, I was perfectly in sync with my co-performer.