Costume Institute Gala Katie Holmes white gown

Katie Holmes looks fantastic, but she's not exactly sticking to the 2013 Costume Institute Gala's punk theme with this Grecian goddess-inspired white Calvin Klein dress! Then again, unless you're Miley Cyrus or Kristen Stewart, it is pretty difficult to pull off this look naturally...

Sienna Miller (who was accompanied by baby daddy Tom Sturridge) also wore a long white gown, but from the clutch to the studded leather jacket and studded headband, she was way more into the night's theme: