Leonardo DiCaprio is to play multiple personality disorder sufferer Billy Milligan on the big screen.

The Wolf Of Wall Street star, who has expressed his desire for the role for over 15 years since 1997, will portray the man, who claimed to possess up to 24 different personalities, in The Crowded Room, according to the Hollywood Reporter.

Billy (right) with attorney Steve Thompson (AP Photo/The Columbus Dispatch, Gordon Kuster Jr)
Billy Milligan (right) with attorney Steve Thompson (Gordon Kuster Jr/The Columbus Dispatch/AP)

Billy, who died in December 2014 at the age of 59, successfully used multiple personality disorder as a defence in the courtroom, pleading insanity, and was acquitted from robbery and rape in the late 1970s.

The Crowded Room, which Leonardo will also co-produce, will be adapted from Daniel Keyes’ 1981 book, The Minds Of Billy Milligan, by screenwriters Jason Smilovic and Todd Katzberg.

The film has been in development for nearly two decades, with James Cameron tipped to write and direct it in the early 1990s.

Matthew McConaughey
Matthew McConaughey was attached to the role of Billy at one point (Ian West/PA)

Directors Joel Schumacher and David Fincher were also attached at various points, while Matthew McConaughey, Johnny Depp, Brad Pitt, Sean Penn and John Cusack have all been linked to the lead role.