With the countdown clock to Halloween Costumes ticking down, celebrities are getting a big warmup for this week’s festivities. Not only have we seen new costumes at Matthew Morrison’s star-studded bash and the festive Casamigos Tequila party, but stars have also been showing off their spooky and sexy looks on Instagram. 
Paris Hilton took a racy picture with nothing but a mask on, and Chord Overstreet looked prepared to give partygoers their Miranda rights. That’s just the beginning of the fun — scroll through to see stars dressed as everything from rock stars to superheroes, and if you can’t get enough of the costume madness, check out the 27 times celebrities channeled other celebrities for Halloween!
Carmen Electra
Carmen did her best Katy Perry look for Halloween.
Perrey Reeves
The actress donned a purple Catwoman suit.
Gerard Butler
Yep, that’s the actor in his Captain America ensemble.
Ashley Madekwe
The Revenge star paid homage to Heath Ledger’s performance as the Joker in a nurse’s uniform in 2008’s The Dark Knight.
Zelda Williams and Jackson Heywood
The daughter of the late Robin Williams donned a pink dress and black makeup, while her date channeled Tom Cruise in Top Gun.
Michelle Trachtenberg
The actress nailed the “Black Dahlia” look.
Randy Couture
The martial artist and actor showed some skin as a fighter, while his companion played an adoring ring girl.