Simon Cowell partied with lingerie-clad models at the infamous Playboy mansion on Saturday night (08.08.09).

The TV mogul attended magazine founder Hugh Hefner's annual Midsummer Night's Dream party, held at the 83-year-old's Los Angeles home.

Jon Voight, Shaquille O'Neal, Jack Osbourne, James Van Der Beek, Ryan Seacrest, Randy Jackson, Shannon Elizabeth, Jon Lovitz and Hefner's former girlfriend Bridget Marquardt also attended the bash.

Hefner has hosted the party on the first Saturday of August for years.

Costumes are essential, with most men - including Hefner - expected to wear their finest pyjamas, while women are invited to don their skimpiest lingerie.

This year, Hefner's new girlfriends Crystal Harris and Karissa and Kristina Shannon stole the show, in miniscule gold bikinis adorned with sparkling beads.

Former 'Girls Next Door' star Bridget was also keen to show off some bronzed skin, squeezing into feathered lime green bra and panties.

Basketball star Shaquille O'Neal was far more casual, wearing a pair of Superman boxers and a plain white T-shirt.

A total of 800 guests attended the party, which saw the mansion decorated in a Greco-Roman style, with ostrich feather fans, painted murals and millions of sequins.