William Shatner
Admiral James T. Kirk
Leonard Nimoy
Capt. Spock/Elevator Voice
DeForest Kelley
Dr. Leonard McCoy
James Doohan
Montgomery Scott
Walter Koenig
Pavel Chekov
Nichelle Nichols
Cmdr. Uhura
Christopher Lloyd
Cmdr. Kruge
Mark Lenard
Ambassador Sarek
Merritt Butrick
Dr. David Marcus
Judith Anderson
Vulcan High Priestess
James B. Sikking
Captain Styles
Phillip R. Allen
Capt. Esteban
Robert Hooks
Admiral Morrow
Carl Steven
Spock...Age 9
Vadia Potenza
Spock...Age 13
Stephen Manley
Spock...Age 17
Joe W. Davis
Spock at age 25
Miguel Ferrer
First Officer
Branscombe Richmond
Klingon Gunner #2
Frank Welker
Spock's Screams
Scott McGinnis
Starfleet Cadet "Mr. Adventure"
Phil Morris
Trainee Foster
Grace Lee Whitney
Commander Janice Rand (Woman in Cafeteria)
Nanci Rogers
Bar Waitress (uncredited)