Brad Pitt Attends Jennifer Aniston's Star-Studded 50th Birthday Party

Nick Maslow

Brad Pitt helped Jennifer Aniston celebrate her 50th birthday.

Pitt was spotted at the actress’ birthday party at the Sunset Tower Hotel in Los Angeles on Saturday, PEOPLE confirms.

Pitt, 55, made a casual entrance at the hotel, where his ex-wife, who turns 50 on Monday, held her big bash. The actor arrived at the hotspot with his long hair slicked back underneath a cap, photos show.

A source tells PEOPLE party guests included Pitt’s ex Gwyneth Paltrow, plus Aniston’s ex John Mayer and his ex Katy Perry, who was joined by boyfriend Orlando Bloom.

George and Amal Clooney, Reese Witherspoon, Robert Downey Jr., Ellen DeGeneres, Barbra Streisand, Keith Richards, Kate Hudson, Laura Dern, Demi Moore and Jennifer Meyer were among the familiar faces at the star-studded fête.

Aniston also celebrated with her Friends costars and good pals Lisa Kudrow and Courteney Cox, whose ex-husband David Arquette attended.

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Brad Pitt

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The following day, Aniston’s pals began wishing the star a happy birthday on social media, sharing their own sweet images taken from the celebration.

“Love these ladies,” Hudson wrote alongside a series of photo booth GIFs on Instagram, in which she posed alongside Aniston and Paltrow. “Celebrated this beauty last night Happy Bday JA! We all love you sooo!”

In her own post, Paltrow wrote, “Happy birthday (last night and tomorrow) to #jenniferaniston our ray of sunshine, example of perpetual goodness. We love you so much and you make 50 LOOK]]>🔥