10/11/2011 04:38 pm ET Updated Dec 11, 2011

Michelle Williams As Marilyn Monroe & Other Off-Screen Style Lookalikes (PHOTOS)

Actresses often undergo drastic changes to physically morph into their movie characters. Some leading ladies like Michelle Williams have not only morphed their bodies but their off-screen style as well.

For Williams, her role as Marilyn Monroe in "My Week With Marilyn" has meant a full fashion transformation: from her Vogue spread to various red carpet outings, Michelle has sported retro looks and bleached blonde hair, channeling the Hollywood icon flawlessly.

Check out Michelle plus six other actresses -- Kate! Sienna! -- who have let their onscreen movie roles influence their offscreen fashion!

Onscreen to Offscreen Lookalikes