Chadwick Boseman Dead at 43: Mark Ruffalo + More Celebrities React

Actor Chadwick Boseman—best known for his role as King T'Challa in Black Panther—died on August 28 after a four-year battle with colon cancer, and celebrities have already posted all over social media to express their condolences.

Mark Ruffalo, Mariah Carey, and Kerry Washington are only a few of the stars who took to social media to honor the 43-year-old actor after the news of his passing broke.

See how celebrities reacted to Chadwick Boseman's passing below.