Jane Fonda, Meryl Streep and more are honoring Redford's massively successful career, which saw Oscars, era-defining films and box office smashes including The Sting, Butch Cassidy and the Sundance Kid and All the President's Men.
"One of the lions has passed. Rest in peace my lovely friend," Streep said in a statement shared with ABC News. Streep and Redford starred in the romance film Out of Africa together in 1985.
The pair starred together in several films throughout their careers, including 1967's Barefoot in the Park and 2017's Our Souls at Night.
Stephen King remembered Redford's importance to the movie industry, writing in a social media post, "Robert Redford has passed away. He was part of a new and exciting Hollywood in the 70s and 80s. Hard to believe he was 89."
Jamie Lee Curtis took to Instagram, sharing a photo of Redford along with a message.