Michael Gambon in Harry Potter and the Prisoner of Azkaban
Richard Harris died after filming the first two Harry Potter movies, with the Dumbledore role thenceforth in the films played by Michael Gambon. He entered the series at a watershed moment with Prisoner of Azkaban, which added some menace and directorial personality to Hogwarts. Though every Potter movie is Certified Fresh, Azkaban is a 91% score over Chamber of Secrets‘ 82%, which would be the franchise high until the final movie.