Actor Leonard Nimoy will forever be known for his decades-spanning role as Mr. Spock in the Star Trek franchise. Though Zachary Quinto and Ethan Peck put their own respectable spins on the Enterprise's trusted Science Officer, it was Nimoy who originated the character and established nearly all of the signature characteristics of Spock and his Vulcan, including the iconic Vulcan salute. From his deadpan delivery to his subtle sense of humor, it's hard to imagine anyone else other than Nimoy playing the role in The Original Series. However, Nimoy was not the only actor considered for the role during Star Trek's long and chaotic development stages.
Along with an actor who became a main player in The Original Series, the role of Spock was also pitched to an actor who went on to win an Academy Award -- Martin Landau.
It is unclear whether Martin Landau was actually offered the part or if he was simply in consideration. Regardless, the veteran actor has been consistently blunt in his reasoning for not pursuing the role. In a 1986 interview with Starlog, Landau said he had no regrets about turning down Spock, saying that he "did not want to be saddled with the role of a character without feeling" and that the role was "the antithesis of why I became an actor." He also said, "It would've been torturous... I would've probably died playing that role." Instead, Landau chose to star as IMF disguise expert Rollin Hand in the original Mission: Impossible television series.
Although an issue of Star Trek: The Magazine said that Gene Roddenberry would've gone to Landau if his first choice, Nimoy, had passed on the role, he had also pitched the role to another -- and familiar -- actor. According to William Shatner's book Star Trek Memories, Roddenberry initially offered DeForest Kelley the role of Spock, but Kelley turned it down because he did not want to play an alien. However, Kelley played the role of Dr. McCoy in The Original Series, who would often be an emotional foil to Spock's overly logical sensibilities.
Nimoy eventually secured the role and appeared in Star Trek's original pilot "The Cage." Though that pilot was thrown out and reworked into the Star Trek we know and love today, Nimoy stayed on as Spock, cementing him as one of pop culture's most beloved and recognizable characters.
In another twist of fate, Nimoy eventually took on the role of the disguise master in Mission: Impossible in the wake of Martin Landau leaving the show and Star Trek's cancellation. As for Landau, after his exit from Mission: Impossible, he received Oscar nominations for his roles in Tucker: The Man and His Dream and Crimes and Misdemeanors, finally winning for playing actor Bela Lugosi in Tim Burton's Ed Wood. He passed away in 2017 at the age of 89.