Prof. Bernard Quatermass
Chief Inspector Lomax
Dr. Tom Brand
Marsh
Work Camp Manager Dawson
Vincent Broadhead, M.P.
The Plant Tour Guide
Jimmy Hall
Paddy Gorman
Ernie the Bartender
E. J. Macleod
Lab Assistant
Kelly
Woman Member of Parliament
Peterson
Sheila
Miss Beal
Mrs. McLeod
Harry
The Police Commissioner
Intern
Super
Chris (uncredited)