3. Robert De Niro
Anyone foolish enough to question film legend Robert De Niro’s dedication to his work need only look to his iconic role as boxer Jake Lamotta in Raging Bull for correction. Robert De Niro trained for the roll with Lamotta himself, trimming fat and building incredible muscle, as well as he fought in actual boxing matches in order to get into character. For scenes portraying the boxing icon’s later years, De Niro then packed on over 60 pounds. That was one hard-earned Oscar.