William Shatner
Prof. Stephen Turner
Lynn Carlin
Barbara
Ossie Davis
Reed
Viveca Lindfors
Mrs. Schnagel
Estelle Parsons
Crossland
Roy Poole
Dr. Goodman
Mike Kellin
Mancuso
Richard McKenzie
Mr. Dennison
Fred J. Scollay
Dr. McBride
Stephen Macht
Dahlquist
Lindsay Crouse
Karen
Charles White
Harry Vogel
Gregory Abels
Lab Technician
Robert Burr
Mr. Hughes
Tom Quinn
Bully in Bar
Billie Lou Watt
Mrs. Carol
Jeff Pomerantz
Professor
W.T. Martin
Mario, the Waiter
Gary Cookson
Lab Technician
John Travolta
Lab Technician (uncredited)