Rihanna [1] brought out the big guns for her inaugural Diamond Ball charity gala in Beverly Hills on Thursday night. The event, which benefits her Clara Lionel Foundation, which is named after her grandparents Clara and Lionel Braithwaite, featured guests like Kim Kardashian [2] and Salma Hayek [3], plus a surprise roasting of the singer from none other than Brad Pitt [4]. While introducing Rihanna for a special performance, Brad joked about RiRi's scandalous image. He said, while looking at pictures of Rihanna's younger days, "I've often asked the very questions you yourself are asking right now — what the f*ck went wrong?" Brad also joked after listing her many accomplishments: "I ask that we stand together by her side and show her our support and our love and say to her the hard words, 'Rihanna, put down that sandwich, get off your ass, and do something. Godd*mn it, just do something with your life.'"

Rihanna [5] wore a Zac Posen gown.

Brad Pitt [6] made a surprise appearance.

Rihanna [7] met up with Salma Hayek [8] on the red carpet.

Kim Kardashian [9] arrived with her mom, Kris Jenner.

Rihanna [10] posed for photos alongside her grandfather Lionel "Bravo" Braithwaite and her mother, Monica Braithwaite.

Nikki Reed [11] and Kat Graham wore sexy ensembles.

Rihanna [12] smoldered in diamonds and dark lipstick.

Adrienne Bailon popped up at the event.