Katy Perry throws early Halloween-inspired birthday party, Kristen Stewart attends without Robert Pattinson

Ahead of Katy Perrys 28th birthday this Thursday, the pop star threw a Halloween-inspired birthday party at Los Angeles Magic Castle.

Perry, who partied along with guests such as on-again/off-again boyfriend John Mayer, Neil Patrick Harris and David Burtka, DJ Skrillex, Kristen Stewart and more, wore a vampire costume.

Her date, Mayer, wore a vampire hunter costume, and even got so into it that he wore a fake nose and chin, E! Online reports.

"Thank you @KatyPerry for having @DavidBurtka and me at your frightfully fun B'day Bash at the @MagicCastle last night," Harris tweeted the day after the event, with a picture of he and Burtka.

Stewart, however, did not bring her recently on-again boyfriend, Robert Pattinson, to the party. Instead, she took Pattinsons friend Marcus Foster, Just Jared reports.

She looked happy and was surrounded by her friends the whole time, a source said of the Twilight star.

Perry, meanwhile, helped Mayer ring in his 35th birthday in New York City last week.

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