Doctor Carter: Rex Robinson (1-2); King Rokon: Roy Skelton (1,4); Intern: Renu Setna (1); Tom Abbott: David Purcell (1); Zazzka: Roy Pattison (1); Guard: Robin Hargrave (1); Professor Owen Watson: Glyn Houston (2-3); Driscoll: Roy Boyd (2-3, uncredited for 3); Miss Jackson: Frances Pidgeon (2-3, uncredited for 3); Elgin: John Cannon (2); Eldrad: Judith Paris (3-4), Stehpen Thorne (4);
Uncredited:
Computer Voice: Roy Skelton; Hospital Nurse: Libby Ritchie (1); Path Lab Technicians: John Delieu (1), Derek Suthern (1); Double for Doctor Carter: Max Faulkner (2); Security Guards: Michael Dewlid (2), Barry Summerford (2); Radiation Suit Men: David Cleeve (2), Keith Simmons (2); Control Room Technicians: (all 2) Julia Burnett, Bruce Guest, Mark Holmes, Rosemary Jollisse, Kenneth Thomas; Nunton Complex personnel: (all 2) Douglas Auchterlonie, Margaret Pilleaud, Roger Salter, Lionel Sansby, Sonia Stratton; Frozen Operator (Technician Obarl): Peter Roy (4); Extras: Peter Bush (1), Carl Edwards (1), Alan Evans (1), Brian Gear (1), Tim Hooper (3), Bruce Hubble (1), David Hyde (1), Colin Jaggard (1), Simon Jones (1), Robert Lee (2), Paul Nicholason (2), Bob Peters (1), Ken Taylor (1), John Telfer (1), Robert Tucker (2), Michael Wadsworth (1), Roy Wadsworth (3);
ARC Quarry, Crowhall, Avon; Oldbury Nuclear Power Station, Avon;