Ian Somerhalder, Nina Dobrev, and Derek Hough Credit: Beacher's Madhouse

Nina Dobrev was feeling the love on her 24th birthday! The Vampire Diaries actress was feted by her boyfriend and costar Ian Somerhadler -- and a handful of celebrity pals! -- during Dior's Hollywood Glamour Dinner at Chateau Marmont in West Hollywood Jan. 9.

The TV star was toasted by Pitch Perfect's Anna Kendrick, Twilight's Nikki Reed and Dancing With the Stars' Derek Hough, a source tells Us Weekly. By the end of the night, "Nina hopped into the back seat of her town car and rolled down her window to sign autographs for a couple enthusiastic fans."

Dobrev thanked her fans for their celebratory tweets several days later. "I know it's delayed but if you'll believe it I haven't been able to get on Twitter since midnight the day before my birthday!" she wrote Jan. 12. "All you amazing people crashed my account with your sweet messages and birthday wishes!"

"Thank you," the actress added. "It was a very special day! You rock!"

Though Dobrev was recently rumored to be engaged to Somerhalder, 34, a rep assured Us the reports are "totally untrue.