7. Robert De Niro
Robert De Niro is regarded as one of the greatest actors who has ever lived, and it's not without good reason; putting his accolades aside, he has starred in some of the most iconic cinematic roles of all time, and cements himself among the trio of actors frequently cited as the best - himself, Al Pacino and Marlon Brando. The Italian-American actor proves that it took plenty of hard work to get there, though; for Scorsese's New York, New York, he trained on the saxophone until he reached a professional grade, became a professionally-rated boxer for his Raging Bull, and for a two-one punch on that film, also "ate his way around Europe" to gain the weight necessary for the film's late-day, post-boxing scenes. As for arguably his best and most iconic performance as Travis Bickle in Taxi Driver, De Niro went to the lengths of spending 3 months working 12-hour shifts at a taxi rank, no doubt helping to fuel the despair that oozes out of his turn. Oh, and for Cape Fear he had his teeth ground down to give him that more menacing look. Dedication or what? And this is only #7.