It wouldn't be Halloween without Matthew Morrison's celebrity-filled birthday party.
The Glee star, who turns 35 on Oct. 30, hosted his fourth annual masquerade soiree at new Hollywood hot spot Warwick.
Morrison came as Andy Warhol, taking a photos on a camera around his neck just like the late artist did. Morrison's fiancé Renee Puente donned a blond bob wig and mini dress as Warhol's muse, Edie Sedgwick.
The award for most unrecognizable celeb goes to Colton Haynes, who went all out as a very messy looking old lady. The Arrow hottie covered his face with prosthetics and slipped into a bra, panties and a grey wig and smeared on some red lipstick for the night.
He and his Teen Wolf pal Holland Roden (in all blue as "Never Nude" Tobias from Arrested Development) posed for slightly NSFW pics.
Lauren Conrad, dressed as fairy with long blond locks in an updo, was one of the first guests to arrive. On her arm was her law school fiancé William Tell as a dentist with a nametag reading, "Chip Molar, DDS."
The former The Hills star held court in a VIP area that also included JC Chasez in very short red swim trunks and a yellow t-shirt emblazoned with, "Baywatch."
Morrison's Glee costar Chris Colfer used battery operated lights for his R2-D2 costume. He was joined by pal covered in gold as C-3PO.
Kristen Chenoweth made for one adorable SWAT team member as she held hands with and kissed a mystery man in a stormtrooper suit.
Other celebs included Chace Crawford as a cop (we're still unsure if his mustache was real!) and The Blind Side star Quinton Aaron as a bishop. Revenge's Josh Bowman and a pal squeezed through the Dos Equis-sponsored bash in large sumo wrestler costumes. Chord Overstreet remained his hot self as Jax from Sons of Anarchy.
For more on the party and to see our exclusive interview with Morrison, tune into E! News tomorrow at 7 p.m. and 11:30 p.m.