William Shatner as Admiral James T. Kirk

Leonard Nimoy as Mr. Spock

DeForest Kelley as Dr. Leonard 'Bones' McCoy

James Doohan as Cmdr. Montgomery 'Scotty' Scott

George Takei as Lt. Cmdr. Hikaru Sulu

Walter Koenig as Lt. Pavel Chekov

Nichelle Nichols as Lt. Cmdr. Uhura

Stephen Collins as Captain William Decker

Persis Khambatta as Lt. Ilia / The Probe

Majel Barrett as Dr. Christine Chapel

Grace Lee Whitney as CPO Janice Rand

Mark Lenard as Klingon Captain

Billy Van Zandt as Alien Boy

Roger Aaron Brown as Epsilon Technician

Gary Faga as Airlock Technician

Franklyn Seales as Crew Member

Joel Kramer as Klingon Crewman

David Gautreaux as Cmdr. Branch

John Gowans as Assistant to Rand

Howard Itzkowitz as Cargo Deck Ensign

Jon Rashad Kamal as Lt. Cmdr. Sonak

Marcy Lafferty as Chief DiFalco

Michele Povill as Lieutenant

Jeri McBride as Technician

Terrence O'Connor as Chief Ross

Michael Rougas as Lt. Cleary

Susan O'Sullivan as Woman

Ralph Brannen as Crew Member

Ralph Byers as Crew Member

Paula Crist as Crew Member

Iva Lane as Crew Member

Momo Yashima as Crew Member

Jimmie Booth as Klingon Crewman

Dave Moordigian as Klingon Crewman

Tom Morga as Klingon Crewman

Tony Rocco as Klingon Crewman

Joel Schultz as Klingon Crewman

Craig Thomas as Klingon Crewman

Edna Glover as Vulcan Master

Norman Stuart as Vulcan Master

Paul Weber as Vulcan Master

Joshua Gallegos as Security Officer

Lisa Chess as Yeoman

Leslie C. Howard as Yeoman

Sayra Hummel as Technical Assistant

Junero Jennings as Technical Assistant

Christopher Doohan as Extra (uncredited)