A supporting actor or actress — a performer who supports the lead role in a play, film, or drama, often playing an important secondary part.
その映画で彼は印象的な助演者として注目された。
He was noticed as an impressive supporting actor in that film.
助演者の演技が作品全体の雰囲気を高めている。
The supporting actors' performances enhance the overall mood of the work.