8. Marlon Brando - The Men (1950)
Although Marlon Brando is often considered to be one of the greatest - if not the greatest - actors of all time, his debut flick The Men still remains relatively unknown to mainstream audiences.
The plot, which is set around a WWII veteran who is wounded in combat and struggles to rehabilitate himself, is genuinely affecting in places - this might be, partly, due to the research that Marlon Brando undertook prior to filming: he spent almost a month confined to a ward in an army hospital, using only a wheelchair as a means to get about, whilst he studied the patients.
At the time of shooting, producers on The Men were worried about Brando's idiosyncratic acting style - they thought he mumbled his lines too much, and that audiences wouldn't take to the way Brando didn't seem to "respond" to the other actors on set. This proved to be of little concern, of course, as audiences everywhere would eventually come to embrace Brando's acting chops and naturalistic performance style with gusto.
Though he's undoubtably an actor of great means, Brando's stay at the army hospital here was sure to have helped with all the emotion factors that such a role demanded, and is one of the earliest examples in cinematic history of an actor taking the research process quite so seriously.