George Clooney as Chris Kelvin

Natascha McElhone as Rheya

Viola Davis as Gordon

Jeremy Davies as Snow

Ulrich Tukur as Gibarian

Michael Ensign as Friend

John Cho as DBA Emissary

Morgan Rusler as DBA Emissary

Shane Skelton as Gibarian's Son

Donna Kimball as Mrs. Gibarian

Elpidia Carrillo as Friend

Kent Faulcon as Patient

Lauren Cohn as Patient

Jennie Baek as Passenger (uncredited)

Tony Clemons as Dinner Guest (uncredited)

Annie Morgan as Nurse (uncredited)

Antonio Rochira as Party Guest (uncredited)

Jude S. Walko as City Dweller (uncredited)