10 Actors Who Scared Themselves

10. Natalie Portman Worried She Was "Going To Die" - Black Swan

Darren Aronofsky is one of the most uncompromising filmmakers working today, and actors who sign up to star in his movies are clearly encouraged to entrench themselves as deeply as possible in their characters - see: Mickey Rourke in The Wrestler and Jennifer Lawrence in Mother!

And then there's Aronofsky's Black Swan, which scooped Natalie Portman a Best Actress Oscar for her performance as Nina Sayers, a ballet dancer whose grasp of reality begins to slip amid fierce competition.

But between the dark subject matter and intense training regimen Portman underwent for the role - including losing 20 pounds and working out up to eight hours per day - she ended up becoming fearful for her own life. She said:

"There were some nights that I thought I literally was going to die... It was the first time I understood how you could get so wrapped up in a role that it could sort of take you down."

Portman later followed up by admitting that she "probably should have gone into rehab" following the completion of filming, though instead threw herself headlong into shooting the first Thor film.

Portman's career and credibility certainly benefitted enormously from her committed to the role, even if she got a first-hand glimpse at how terrifying such extreme commitment can be.