Note this is a cast page
Shatner reprised his role as Kirk while also serving as director.
William Shatner as James T. Kirk. Shatner practiced aerobics and strength training daily to prepare for the role. The physical activity and directing duties meant he woke at 4 a.m. every day during filming, no matter what time he fell asleep.
Leonard Nimoy as Spock, the Enterprise's half-Vulcan, half human science officer. Nimoy noted The Final Frontier was the most physical film in the series, which reflected Shatner's energetic sensibility and what he enjoyed doing most on the show — "running and jumping". Nimoy recalled Shatner's attempts to instruct him in riding a horse, although Nimoy had ridden many horses bareback when playing American Indian roles for Republic Pictures serials.
DeForest Kelley as Leonard McCoy, chief medical officer. Kelley also noted the physicality required for the film and enjoyed doing things that he had not been asked to do in years. "I was very pleased to see that he [Shatner] brought it along in fine style," he said. Kelley noted that his own ambition to direct had deserted him after seeing difficulties Nimoy faced directing the previous two Star Trek films.
The other members of the USS Enterprise-A crew include chief engineer Montgomery Scott(James Doohan), helmsman Hikaru Sulu (George Takei), navigator Pavel Chekov (Walter Koenig), and communications officer Nyota Uhura (Nichelle Nichols). Takei said that despite studio pressure to complete the film on time, Shatner maintained a creative and enthusiastic atmosphere on set. "I have enormous admiration for his ability to block that kind of pressure from seeping on to the set." Takei said that he found the biggest challenge of the film was learning to ride horses. Moreover, Takei acknowledged, "despite our sometimes strained personal history, I found working with Bill [Shatner] as a director to be surprisingly pleasant."
Laurence Luckinbill plays Sybok. Sean Connery was originally contacted to star in the role, but was busy with Indiana Jones and the Last Crusade. Shatner discovered Luckinbill by chance; channel surfing late one night, he saw him perform as Lyndon Baines Johnson.When Shatner called to offer him the role, Luckinbill accepted immediately.
Casting director Bill Shepard was in charge of filling additional roles. He combed through initial auditions with promising actors, then presented his choices to Shatner. Both men called the actors back as many as two or three times before each role was cast. Additional players include Todd Bryant as Klingon Captain Klaa, with Spice Williams-Crosby as Vixis, Klaa's lieutenant. Bryant was playing ping pong at a beach party when a casting director offered him the role. Bryant performed his audition twice, as Shatner requested that he repeat his performance speaking in Klingon. Williams-Crosby thought Vixis was Kirk's girlfriend when she arrived for her audition, but recalled afterwards that it was "fun" to play a villain. David Warner, Charles Cooper and Cynthia Gouw play the Federation, Klingon, and Romulan ambassadors to Nimbus III. Warner did not audition, but agreed to the role after Shatner swore that his character would survive the film. The director originally intended George Murdock to play the Klingon diplomat Korrd, but changed his mind on seeing Cooper's performance. Murdock was recast as the "God" entity. Bill Quinn played McCoy's father in one of his last roles. Producer Harve Bennett made a cameo as a Starfleet admiral.