It's no secret that some actors go to extremes when gearing up for a role -- whether it be losing weight, gaining weight or dying their hair to accurately portray a character. Other times, it's the makeup artists who take things to another level, completely transforming a celebrity's face in order to make a fictional or nonfictional person a reality onscreen.
From Charlize Theron's transformation in "Monster" to Robin Williams' "Mrs Doubtfire" look, here are 19 stars whose film personas will make you do a double-take:
Steve Carell in "Foxcatcher"
Getty/Sony Pictures Classics
Carell plays millionaire and coach John du Pont in the 2014 film, which is based on the true story of Mark Schultz, an Olympic wrestler whose relationship with sponsor du Pont and brother Dave Schultz led to unlikely circumstances.
Chadwick Boseman in "Get on Up"
Boseman transformed into the legendary James Brown for the 2014 film about the singer's rise from poverty to fame.
Meryl Streep in "The Iron Lady"
Streep played British Prime Minister Margaret Thatcher in the 2011 film.
Matthew McConaughey in "Dallas Buyers Club"
In the 2013 movie, McConaughey played AIDS patient Ron Woodroof, and lost 40 pounds for the role.
Charlize Theron in "Monster"
Theron won an Oscar for her portrayal of Aileen Wuornos, a Daytona Beach prostitute who became a serial killer.
Ashton Kutcher in "Jobs"
Getty/ Open Road Films
Kutcher played Steve Jobs in the 2013 film about the entrepreneur's ascension from college dropout to one of the most revered creators of the 20th century.
Elizabeth Banks in "The Hunger Games" franchise
Banks plays the flamboyant and quirky Effie Trinket in the beloved book-turned-movie series.
Daniel Day-Lewis in "Lincoln"
In the 2012 film, Day-Lewis took on the role of Abraham Lincoln, for which he won an Academy Award.
Christian Bale in "American Hustle"
Bale portrayed con man Irving Rosenfeld in the 2013 dramedy. He gained a significant amount of weight for the role, as well.
Rooney Mara in "The Girl with the Dragon Tattoo"
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Mara looks nothing like herself in the 2011 movie, based on the best-selling book of the same name.
Cate Blanchett in "I'm Not There"
Blanchett wowed as Bob Dylan in the 2007 film by Todd Haynes.
Robert De Niro in "Raging Bull"
De Niro looked almost unrecognizable as boxer Jake La Motta in Martin Scorsese's 1980 film.
Ben Kingsley in "Gandhi"
Getty/ Columbia Pictures
Kingsley portrayed the famed leader in the 1982 movie and won an Oscar for his work.
Hilary Swank in "Boys Don't Cry"
Getty/Fox Searchlight Pictures
Swank was barely recognizable as she played transgender man Brandon Teena in the 1999 film, for which she won an Academy Award.
John Travolta in "Hairspray"
Getty/New Line Cinema
Who can forget Travolta as Edna Turnblad in the screen version of the beloved musical "Hairspray"?
Eddie Murphy in "The Nutty Professor"
Murphy turned into the lovable Sherman Klump in the 1996 comedy.
Jennifer Lawrence in "X-Men" films
Getty/Twentieth Century Fox
JLaw goes blue for her role as Raven aka Mystique in the "X-Men" movies.
Jim Carrey in "How the Grinch Stole Christmas"
Carrey is barely recognizable as Dr. Seuss character Grinch in the 2000 holiday movie.
Robin Williams in "Mrs. Doubtfire"
Williams' memorable performance as Mrs. Doubtfire will always put a smile on our faces.