Jason Segel (Peter Bretter), Kristen Bell (Sarah Marshall), Mila Kunis (Rachel Jansen), Russell Brand (Aldous Snow), Bill Hader (Brian Bretter), Paul Rudd (Chuck), Maria Thayer (Wyoma), Liz Cackowski (Liz Bretter), Jack McBrayer (Darald), Branscombe Richmond (Keoki), Carla Gallo (Gag Me-Girl), Jason Bateman (Detektiv in 'Animal Instincts'), William Baldwin (Detective Hunter Rush), Taylor Wily (Kemo), Brittany Ross (kreischende Freundin), Ahna O'Reilly (Leslie), Gedde Watanabe (Hotelmanager), Jonah Hill (Matthew, der Kellner), June Diane Raphael (Ann an der Bar), Da'Vone McDonald (Dwayne, der Barmann), Kirk Fox (Mixer), Cynthia Lamontagne (Barfrau), Peter Salett (Keyboardspieler), Peter Lewis (Verdächtiger in 'Animal Instincts'), Steve Landesberg (Dr. Rosenbaum), Billy Bush (er selbst), Murray Miller (Fotograf), Kala Alexander (Greg)