Darren McGavin as Harry Forbes

Gary Collins as Steve Bancroft

Robert Vaughn as Gordon Cain

James Hampton as Lew Price

Philip Abbott as Frank Morrison

Joseph Campanella as Frank Lafferty

Pamela Bellwood as Sarah Michaels

Tom Hallick as Phil Cameron

Steven Keats as Paul Bannister

William Schallert as Professor Mills

Cliff Osmond as Sheriff Barlow

Andrew Bloch as Neal Kelso

Stuart Pankin as Sam Tate

Betty Ann Carr as Flo Mattson

H.M. Wynant as Flight Director

Bill Zuckert as Ace Landon

Michael Irving as MIB #1

Bruce Katzman as MIB #2

Eddie Carroll as MIB #3

Jesse Bennett as MIB #4

Robert Bristol as Helicopter Pilot

J.R. Clark as Judd Gates

Craig Clyde as Captain Wyatt

John William Galt as NASA Official

Anne Galvan as Technician

Ken Hepner as Pilot

Peter Liakakis as Barman

Debrah Macfarlane as Female Specimen

Chesley Noone as A.F. Captain

H.E.D. Redford as CAPCOM Officer

Max Robinson as Payload Officer

Ocie Robinson as A.F. Guard

Michael Ruud as George Turner

Scott Wilkinson as Flight Activity Officer