LOS ANGELES: Jennifer Aniston threw a star-studded birthday party for her fiance Justin Theroux at their $21 million Bel Air mansion on Saturday, Aug. 10. Guests including Ben Stiller, Isla Fisher, Sacha Baron Cohen, Dax Shepard and more enjoyed celebrating Justin’s 42nd birthday. Before the party, the ladies got ready inside (Aniston’s hair stylist Chris McMillan was on hand to style the former Friends star), while Theroux, an actor-screenwriter, hung out with his guys outside, reports Us Weekly. “Several of Justin’s friends spent the afternoon at the house hanging out by the pool with him and celebrating his birthday,” an eyewitness said. –SS