It's a rite of passage for any actor in search of an Oscar/acceptance. Putting the alien bounty hunter roles to the side for once and focusing on the truth.
We've assembled 50 actors who've kept it real and paired them up with their non-fictional counterpart. We want you to let us know which actor looks the most and least like the real-life character they've played.
Keira Knightley (Domino)
Character: Domino Harvey
Trivia: The real Domino died from an accidental overdose just months before the film was released.
James Franco (127 Hours)
Character: Aron Ralston
Trivia: Cillian Murphy was director Danny Boyle's first choice to play Aron.
Angelina Jolie (A Mighty Heart)
Character: Mariane Pearl
Trivia: Despite criticism of a white actress playing a mixed-race role, Mariane Pearl herself had asked Jolie to play the part
Joaquin Phoenix (Walk The Line)
Character: Johnny Cash
Trivia: Johnny Cash approved Phoenix for the role after he saw Gladiator yet Cash is 6" taller than him.
Warren Beatty (Bonnie & Clyde)
Character: Clyde Barrow
Trivia: Before deciding to play the role himself, producer Beatty wanted Bob Dylan to star.
Chris Cooper (Breach)
Character: Robert Hansenn
Trivia: The real Hansenn was obsessed with Catherine Zeta-Jones. This is referenced in the film when investigators find a couple of her films in his belongings.
Meg Ryan (Against The Ropes)
Character: Jackie Kallen
Trivia: Michelle Pfeiffer turned down the role.
Robert De Niro (Raging Bull)
Character: Jake LaMotta
Trivia: Jake LaMotta thought that De Niro was such a good boxer that he would have been happy to be his manager.
Philip Seymour Hoffman (Capote)
Character: Truman Capote
Trivia: In 2006, the role of Truman Capote was also played by Toby Jones in Infamous.
Denzel Washington (Malcolm X)
Character: Malcolm X
Trivia: Oliver Stone was originally set to direct and Washington was his first choice as well.
Angelina Jolie (Changeling)
Character: Christine Collins
Trivia: Both Hilary Swank and Reese Witherspoon lobbied for the role of Christine Collins.
Michael Sheen (The Damned United)
Character: Brian Clough
Trivia: Clough's widow was against the film as she said the majority of the events depicted didn't happen.
Eric Bana (The Other Boleyn Girl)
Character: Henry VIII
Trivia: Bana avoided all other films and TV shows featuring Henry VIII to keep his portrayal independent.
Kevin Costner (The Untouchables)
Character: Eliot Ness
Trivia: Harrison Ford was offered the role but turned it down.
Hilary Swank (Amelia)
Character: Amelia Earhart
Trivia: Although Swank was a pilot-in-training, movie bosses opted for professional pilots for insurance reasons.
Robert Downey Jr (Chaplin)
Character: Charlie Chaplin
Trivia: Jim Carrey was originally considered for the role.
Benicio Del Toro (Che)
Character: Che Guevara
Trivia: Del Toro had always been the first choice for the lead yet Val Kilmer was considered as a secondary option.
Dustin Hoffman (Lenny)
Character: Lenny Bruce
Trivia: Al Pacino was originally considered for the role.
Gary Busey (The Buddy Holly Story)
Character: Buddy Holly
Trivia: Busey had previously been cast as Holly's drummer in a previous attempt at a biopic which was ultimately cancelled.
Julia Roberts (Erin Brockovich)
Character: Erin Brockovich
Trivia: The real Brockovich is right-handed while Roberts is left-handed meaning the Hollywood star had to learn how to sign her name with her right hand for the shoot.
Anthony Hopkins (Nixon)
Character: Richard Nixon
Trivia: The role was turned down by Tom Hanks, Jack Nicholson, Robin Williams, Warren Beatty and John Malkovich.
Liam Neeson (Kinsey)
Character: Alfred Kinsey
Trivia: It was the first film permitted to show human genitalia uncensored in Japan.
Russell Crowe (Cinderella Man)
Character: James J. Braddock
Trivia: James J. Braddock's granddaughter Rosemarie DeWitt stars in the film as his neighbour.
Val Kilmer (The Doors)
Character: Jim Morrison
Trivia: Prior to the audition, Val Kilmer memorized the lyrics to all songs written by Jim Morrison
Leonardo DiCaprio (The Aviator)
Character: Howard Hughes
Trivia: Jim Carrey was originally considered for the role.
Marion Cotillard (La Vie En Rose)
Character: Edith Piaf
Trivia: To look the part, Cotillard shaved back her hairline and shaved her eyebrows off.
Woody Harrelson (The People Vs Larry Flynt)
Character: Larry Flynt
Trivia: Porn baron Larry Flynt apparently wanted Michael Douglas to portray him on screen.
Naomi Watts (Fair Game)
Character: Valerie Plame
Trivia: Nicole Kidman, real-life best friend of Watts, was originally set to star.
David Strathairn (Good Night And Good Luck)
Character: Edward Murrow
Trivia: Strathairn, a non-smoker, smoked pipe tobacco in his prop cigarettes while playing Murrow.
Jim Carrey (Man On The Moon)
Character: Andy Kaufman
Trivia: Director Milos Forman couldn't decide between Edward Norton and Jim Carrey for the role so left it to the studio to decide.
James Woods (Ghosts Of Mississippi)
Character: Byron De La Beckwith
Trivia: The real De La Beckwith was residing in jail, less than a mile away from where the film was being shot.
Jesse Eisenberg (The Social Network)
Character: Mark Zuckerberg
Trivia: Shia LaBeouf turned down the film saying it wasn't a "Warren Beatty-style game-changer".
Richard Gere (The Hoax)
Character: Clifford Irving
Trivia: The real Irving was hired as a technical advisor yet asked that his name be taken off the credits as so much was changed.
Denzel Washington (Cry Freedom)
Character: Steve Biko
Trivia: Director Richard Attenborough cast Denzel Washington as activist Steve Biko after spotting him in popular US hospital drama St. Elsewhere.
Hayden Christensen (Shattered Glass)
Character: Stephen Glass
Trivia: The real Glass turned down the chance to work on the film.
Matt Damon (Invictus)
Character: François Pienaar
Trivia: Matt Damon is shorter than the real Pienaar but director Clint Eastwood utilised camera angles to make him look the part.
Josh Brolin (W)
Character: George Bush
Trivia: Christian Bale pulled out of the role at the very last minute.
Johnny Depp (Public Enemies)
Character: John Dillinger
Trivia: Leonardo DiCaprio was originally set to star.
Jamal Woodard (Notorious)
Character: Christopher 'Biggie' Wallace
Trivia: Biggie's son plays a young version of his father in the film.
Ben Affleck (Hollywoodland)
Character: George Reeves
Trivia: Hugh Jackman was originally set to play the part but pulled out.
Kristen Stewart (The Runaways)
Character: Joan Jett
Trivia: When Jett first heard Stewart singing one of her songs on tape, she thought it was a mistake and the tape was actually her.
Colin Firth (The King's Speech)
Character: King George VI
Trivia: The role was written with Paul Bettany in mind but he turned it down.
Jamie Foxx (Ray)
Character: Ray Charles
Trivia: During filming Jamie Foxx wore eye prosthetics that prevented him from seeing a la Charles.
Rhys Ifans (Mr Nice)
Character: Howard Marks
Trivia: Marks and Ifans are good friends in real life.
Charlize Theron (Monster)
Character: Aileen Wuornos
Trivia: The real Wuornos gave the director permission to read through hundreds of private letters.
Sean Penn (Milk)
Character: Harvey Milk
Trivia: Penn wore a prosthetic nose, altered teeth, a redesigned hairline and contact lenses for his portrayal of gay activist and politician Harvey Milk.
Forest Whitaker (The Last King Of Scotland)
Character: Idi Amin
Trivia: Whitaker stayed in character, even when he was off set.
Michael Sheen (The Queen)
Character: Tony Blair
Trivia: Sheen has also played Tony Blair in The Deal and The Special Relationship.
Denzel Washington (The Hurricane)
Character: Rubin 'Hurricane' Carter
Trivia: Washington trained for over a year with a boxing coach.
Liam Neeson (Schindler's List)
Character: Oskar Schindler
Trivia: Stellan Skarsgård was considered for the role.