Given the task definition and input, reply with output. In this task, you are given a question. You have to answer the question based on your information.

Sid Avery, was an American photographer and director who was best known for capturing the private moments of legendary Hollywood celebrities like which American actor, film director and political activist, and helped to popularize the Stanislavski system of acting, studying with Stella Adler in the 1940s?
Marlon Brando