Stella Adler (February 10, 1901 – December 21, 1992) was an American actress, and for decades was regarded as America's foremost acting teacher.

Born in New York, New York, Miss Adler was a member of the Adler acting dynasty, the daughter of Sara and Jacob P. Adler, and the sister of Luther Adler. Miss Adler was the only American actor to be instructed in the art of acting by Konstantin Stanislavsky. Stella Adler was a prominent member of the Group Theatre, but differences of opinion versus Lee Strasberg over the correct teaching of Stanislavky's methods contributed to the ulimate break-up of the group.

She was Marlon Brando's first influential acting teacher. He met her through his sister, who was studying drama with Adler, and decided to take drama as well. (He had been considered unsuitable for the army and had been expelled from the military school that his father had sent him to.) Stella Adler believed when she met him that he would be the best American actor in theater before the end of the year.

From 1926 until 1952 Adler appeared regularly on Broadway. She only appeared in three films including Shadow of the Thin Man (1941).

She died in Los Angeles, California from heart failure.