In the late '60s Marlon Brandon's career was taking a turn for the worse. He hadn't had a commercial hit in a few years, and he was building a bad reputation for being difficult to work with. Apparently, he was very unwilling to memorize his lines on set and often confronted directors with odd requests.
However, he had a couple of fans in director Francis Ford Coppola and Mario Puzo, who wrote The Godfather with Brando in mind. Coppola had Brando submit a make-up test and felt electrified by what he saw. He really wanted Brando to play Vito Corleone.
Paramount Studios, however, did not want to deal with the temperamental actor. Eventually, though, the studio heads saw the screen test and decided to allow Brando to work on the movie. The rest is history, it was a mid-career turning point for Brando, who went on to achieve even bigger fame than he had before.