4. Gary Oldman in Sid and Nancy
The Metamorphosis: In Oldman's breakout role, he became the infamous Sid Vicious, bassist for the Sex Pistols, in a film about Vicious's relationship with his girlfriend, Nancy Spungen. Vicious was an a emaciated heroin addict, and Oldman was nothing if not committed. He didn't go as far as using heroin himself to properly embody Vicious,
but...The Method: ...He did subsist on a diet of "steamed fish and lots of melon."
The Damage: At one point, Oldman was hospitalized. Going a bit too far, methinks.
Was it Worth It? It launched Oldman to stardom, although he didn't receive too much awards attention for it (the Oscars were apparently unaware of his existence until
Tinker Tailor Soldier Spy). So yes.