George Maharis as Lee Barrett

Richard Basehart as Dr. Gregor Hoffman

Anne Francis as Ann Williams

Dana Andrews as Gen. Williams

John Larkin as Dr. Leonard Michaelson

Richard Bull as Eric Cavanaugh

Frank Sutton as Henchman Donald

Ed Asner as Henchman Veretti

Simon Oakland as Tasserly

John Anderson as Agent Reagan

John Clarke as Guard Lt. Raskin

Hari Rhodes as Guard Lt. Johnson

Martin Blaine as Martin

Henry Beckman as Dr. Baxter

Harry Lauter as Fake SDI Agent

James Hong as Dr. Yang

Russ Bender as Desk Guard Mason

Harold Gould as Dr. Ostrer (uncredited)

Lee Remick as Waitress

William Bryant as Lead Agent "X-Ray", drives car

James Doohan as Second Agent "X-Ray", scratches hand

Michael Barrier as Helicopter Pilot Henchman

Tol Avery as Detective Captain at Baseball Stadium

John Hubbard as Guard