Charlize Theron, "Monster" (2003)(01 of26)
Open Image ModalWho knew makeup could turn one of Hollywood's most beautiful people into someone so unrecognizable? When Charlize appeared on screen as serial killer Aileen Wuornos we couldn't believe our eyes. She went on to win the Oscar for Best Actress, an accolade we think was well deserved. (credit:Remstar Films)
Charlize Theron, 2004(02 of26)
Open Image ModalHolding her Best Actress statue for her role in "Monster." (credit:Getty Editorial)
Meryl Streep, "The Iron Lady" (2011)(03 of26)
Open Image ModalStreep has been nominated more than any actor ever for both the Oscars and the Golden Globes -- 18 times and 28 times respectively -- so we're used to seeing her take on a variety of roles. In 2011, she transformed into "The Iron Lady" herself, Margaret Thatcher, and gave an Oscar-winning performance. (credit:Alliance Films)
Meryl Streep 2012(04 of26)
Open Image ModalShowing off her award for Best Actress at the 84th annual Academy Awards. (credit:Getty Editorial)
Glenn Close, "Albert Nobbs" (2011)(05 of26)
Open Image ModalGlenn Close played a woman posing as a man in 2011's "Albert Nobbs." The actress truly disappeared into the role and earned herself a Best Supporting Actress nomination. Unfortunately, she didn't take home the award, but she was up against some stiff competition (re: Meryl Streep). (credit:E1 Films)
Glenn Close, 2012(06 of26)
Open Image ModalWalking the red carpet at the 84th annual Academy Awards show, where she was nominated for her role in "Albert Nobbs." (credit:Getty Editorial)
Hilary Swank, "Boys Don't Cry" (1999)(07 of26)
Open Image ModalHilary Swank transformed into Brandon Teena -- the real-life transgender man the film was about -- and won the Best Actress statue for her moving portrayal. (credit:Fox Searchlight)
Hilary Swank, 2000(08 of26)
Open Image ModalThe actress posing with her Oscar after winning for her role in "Boys Don't Cry." (credit:Getty Editorial)
Jared Leto, "Dallas Buyers Club" (2013)(09 of26)
Open Image ModalJared Leto lost a ton of weight and bleached off his eyebrows to play the role of transgender AIDS victim Rayon in "Dallas Buyers Club." (He even put away his man bun!). The role won the actor/singer a Golden Globe, as well as an Oscar for Best Supporting Actor. (credit:Instagram)
Jared Leto, 2014(10 of26)
Open Image ModalJared Leto holding his Oscar for Best Supporting Actor. (credit:Evan Agostini/Invision/AP)
Mariah Carey, "Precious" (2009)(11 of26)
Open Image ModalThough Mariah herself wasn't nominated for an Oscar for her role as a social worker in "Precious," we're giving her an honourable mention because the film was an awards season favourite. And it's not every day you see the diva totally made-under. (credit:Lionsgate)
Mariah Carey, 2010(12 of26)
Open Image ModalThe diva looking like her usual (fabulous) self. (credit:Getty Editorial)
Javier Bardem, "No Country For Old Men" (2007)(13 of26)
Open Image ModalJavier Bardem technically didn't do too much to change for his role in "No Country For Old Men," but he was lucky enough to receive one of the worst haircuts in movie history. But he got the last laugh when he scooped up the Oscar for Best Supporting Actor. (credit:Alliance Films)
Javier Bardem, 2008(14 of26)
Open Image ModalJavier holding up his Oscar for Best Actor after winning for his role in "No Country For Old Men." (credit:Getty Editorial)
Heath Ledger, "The Dark Knight Rises" (2012)(15 of26)
Open Image ModalHeath Ledger, 2006(16 of26)
Open Image ModalHeath Ledger in 2006. (credit:Getty Editorial)
Rooney Mara, "The Girl With The Dragon Tattoo" (2011)(17 of26)
Open Image ModalRooney Mara, 2012(18 of26)
Open Image ModalRooney on the red carpet at the 84th Academy Awards show where she was nominated for Best Actress for her role in "The Girl With The Dragon Tattoo." (credit:Getty Editorial)
Gwyneth Paltrow, "Shakespeare In Love" (1998)(19 of26)
Open Image ModalGwyneth Paltrow is yet another actress who won an Oscar for a role in which she posed as a male. Gwynnie jumped back and forth between male and female throughout the film, which added to the impressive role, but it was the moustache that sold it for us. (We're sure that's why she won!) (credit:Alliance Atlantis)
Gwyneth Paltrow, 1999(20 of26)
Open Image ModalGwyneth holding her statue after winning Best Actress for "Shakespeare In Love" at the 71st Academy Awards. (credit:Getty Editorial)
Christian Bale, "The Fighter" (2010)(21 of26)
Open Image ModalIf there's one actor in Hollywood who can be described as a chameleon, it's Christian Bale. Whether he's losing weight to play a drug addict (seen here for "The Fighter"), bulking up to play Batman, or sporting a beer-belly and a comb-over as a 1970s con artist in "American Hustle", Bale disappears into every role he signs up for. (credit:Alliance Films)
Christian Bale, 2011(22 of26)
Open Image ModalChristian Bale holds his Oscar statue after winning for his role in "The Fighter." (credit:Getty Editorial)
Melissa Leo, "The Fighter" (2010)(23 of26)
Open Image ModalMelissa Leo, 2011(24 of26)
Open Image ModalHolding her award for Best Supporting Actress after winning for her role in "The Fighter." (credit:Getty Editorial)
Marion Cotillard, "La Vie En Rose" (2007)(25 of26)
Open Image ModalMarion Cotillard, 2008(26 of26)
Open Image ModalMarion posing with her gold statue after winning Best Actress for her role as Edith Piaf "La Vie En Rose." (credit:Getty Editorial)