Who is this dashing celebrity — so modest, so unassuming, so self-assured that he has the courage to show up to a star-studded celebrity event with his face completely covered? If that glimpse of his jumpoff the ever-present Cassie right behind him doesn't give it away instantly, I'll offer you another hint. The "modest and unassuming" thing was a total lie.

The dramatic reveal, plus lots more celeb costumes from last night's parties, after the jump.

You guessed it! Here's Diddy at a NYC Halloween bash hosted by Roberto Cavalli, seen here in an ingenious Karl Lagerfield get up.

Roberto Cavalli's Halloween Party, NYC

Heidi Klum's Halloween Bash, LA
[WI]