Who? Katy Perry
What? The all-singing, costume-crazed Perry was dressed-up as a cartoon character for Halloween, but can you guess which one? Does the big bobbed wig and red school blazer give it away? Her side kick might help...
Where? Hollywood Cemetery in Los Angeles.
Verdict? Ah but of course it's, erm, cartoon character Jane Lane, friend of MTV star Daria. (We didn't get it first time, either). However. Perry's grungy look, complete with lace-up biker boots, was spot on - as was the surly teenage frown.
See a host of spooky star Halloween 2012 costumes below: