Michelle Williams, seen here, stars in "My Week with Marilyn."
In an interview with CBS News correspondent Mo Rocca, Williams said when the star was playing Marilyn Monroe, she wasn't actually being herself.
When asked if Monroe was actually a character, Williams said, "I would say so, and it's beguiling to think maybe that's who she really was, because who wouldn't want to believe that that's possible? But you know, that's just the shell."
Michelle Williams as Marilyn Monroe in "My Week with Marilyn."
Williams told CBS News, "Things that I've read (about Monroe) said she was actually quite, I hate to say it, but ordinary. I read something once that was so moving -- that her face could fall apart in between glances, and then (she could) put it back together -- that it was something she could rearrange in a matter of seconds."
Dougray Scott and Michelle Williams in "My Week with Marilyn." Scott plays Monroe's husband, Arthur Miller, at the time the film takes place. Michelle Williams portrays Marilyn Monroe.
Williams said Monroe felt best when she was in front of an audience. "The audience was the only home that she'd ever really known. And the only people that understood her were the audience -- not the industry that she'd given most of her life to, not the three attempted marriages, but the audience. And even from photos too, I think she sort of got a confirmation of her existence. No father would claim her. Her mother couldn't be consistent with her. And the photos and the audience were sort of proof that she belonged."
Eddie Redmayne in "My Week with Marilyn." Redmayne plays Colin Clark, an employee of Sir Laurence Olivier's, who documents the tense interaction between Olivier and Marilyn Monroe during production of the 1957 comedy "The Prince and the Showgirl."