Jodie Foster (Dr. Eleanor Arroway), Matthew McConaughey (Palmer Joss), James Woods (Michael Kitz), John Hurt (S. R. Hadden), Rob Lowe (Richard Rank), Tom Skerritt (Dr. David Drumlin), David Morse (Ted Arroway), William Fichtner (Dr. Kent Clark), Jena Malone (Ellie Arroway als Kind), Angela Bassett (Rachel Constantine), Max Martini (Willie), Thomas Garner (Ian Broderick), Tucker Smallwood (Missionsleiter), Jake Busey (Joseph), Timothy McNeil (Davio), Geoffrey Blake (Fisher), Vance Valencia (Senator Valencia), Larry King (er selbst), Maximilian Martini (Willie), Donna Kelley (Donna Kelley), Dan Gifford (Jeremy Roth), Conroy Chino (KOB-TV Reporter), Sami Chester (Vernon), Leon Harris (Leon Harris)