Simon Pegg
Neil
Kate Beckinsale
Catherine
Sanjeev Bhaskar
Ray
Rob Riggle
Grant
Robert Bathurst
James Cleverill
Suzy Eddie Izzard
Headmaster
Joanna Lumley
Fenella
Marianne Oldham
Rosie
Emma Pierson
Miss Pringle
Meera Syal
Fiona
Mojo
Dennis the Dog
Robin Williams
Dennis the Dog (voice)
John Cleese
Chief Alien (voice)
Terry Gilliam
Nasty Alien (voice)
Eric Idle
Salubrious Gat (voice)
Terry Jones
Scientist Alien (voice) / Van Driver
Michael Palin
Kindly Alien (voice)
James David Robinson
Steve
Judy Loe
Canteen Lady
Alexa Davies
Sandwich Girl
Ellie Green
Lavender
Brian Cox
Self
James Kermack
Policeman
Brenda Emmanus
Reporter
Neville Phillips
Author
Edward Fisher
Mr. Eriksson
Simon Coleman
Police Inspector
Ronan Summers
Security Man
David Annen
Newsreader
Mairi McHaffie
Newsreader
Gavin Scott
Newsreader
Richard Suchet
Newsreader
Christopher Chesser
Documentary Voice (voice)
Margarita Doyle
Alien Computer Voice (voice) / Señorita Lopez
Jud Charlton
Mortician
Lennon Clarke
Bank Robber
John Bedford
Ray Worshiper
Marli Bland
Ray Worshiper
Basia Forrest
Ray Worshiper
Liliana Gane
Ray Worshiper
Lorna Lacey
Ray Worshiper
Debbie J. Nash
Ray Worshiper
Christian Palmer
Ray Worshiper
Zara Sorensen
Ray Worshiper
Chris Weeks
Ray Worshiper
Robert Jones
Pink Policeman
Chris Daniels
Pink Policeman
Charlie Richards
Pink Policeman
Samuel Timlett
Baby
Lasco Atkins
Party Guest (uncredited)
Hannah Blamires
Photographer (uncredited)
Stuart Budd
Passerby (uncredited)
Marat Khairoullin
Zombie (uncredited)
Jorge Leon
Celebrity (uncredited)
Tremayne Miller
Book Launch Guest (uncredited)
Lockhart Ogilvie
Ray Worshiper (uncredited)
Tony Pankhurst
Father (uncredited)
Alan Yentob
Man at Party (uncredited)