Kristen Stewart And John Mayer Among Guests At Katy Perry's Birthday Bash

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Katy Perry's birthday bash was held in Los Angeles on Friday night (October 19) and celebs in attendance included the likes of Kristen Stewart and current boyfriend John Mayer, as the California girl celebrated her 28th birthday in style.

The 'Firework' singer certainly dressed for the occasion, as she donned a vampire outfit; with BF John opting for a prosthetic nose and chin to go with his zombie hunter outfit. Standard.

One celeb that we didn't expect to see at the party was Kristen Stewart, who was apparently loving every minute as she chatted away to friends. However, the actress was WITHOUT Robert Pattinson and instead partied the night away with his BFF Marcus Foster. Oooo!

She looked happy and was surrounded by her friends the whole time, a source told JustJared.com about 22-year-old Kristens night out at Katy's party, who just happens to be pally with K- Stew's other half Robert Pattinson.

But, although Kristen looked happy, she still refused to join in the dressing up fun and was pictured wearing her usual casual get up, along with Rob's pal Marcus. Boo!

Costume or no costume, Kristen definitely deserves a beverage or 2, especially after dealing with the trauma of her first live interview since the whole affair speculation. Fans definitely didn't like the fact that the 'Twilight' actress cut her web chat short, with one even telling her to 'go to hell'. Harsh, much?

The actress was there to promote the design houses Florabotanica perfume, which the 22-year-old says smells like danger and quite fresh. However, the star's 'lack of interest' in the whole thing has led to fans leaving some rather over the top comments on social networking site Twitter...

When life g! ives you 30mins Kristen Stewart & you only use 15mins youre going to hell, one angry fan, @veraleeon, tweeted.

@RKLover_ tweeted, Dude you were interviewing KRISTEN STEWART and you only used 15 minutes instead of 30?! WHAT IS WRONG WITH YOU?!!!?!

And now we understand why exactly the 'Twilight' star has expressed fears for her life recently, due to fans' ability to constantly stalk the star online.

We hope you partied hard, K-Stew! And a very happy birthday to Katy Perry for October 25th.

Katy Perry & John Mayer celebrate both their birthdays with 'romantic dinner date'

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