Ancient news I know ... but he announced it in April 2010 and I just got wind of it (don't blame me, I was in my happy place at that point) and thought I'd share it with ya'll...

MSNBC wrote:

The longtime “Star Trek” actor, who originated the iconic role of Mr. Spock in the ‘60s TV series and the film franchise that followed, told The Toronto Sun he wants to “get off the stage.” “I don’t think it would be fair to Zachary Quinto,” he said of his successor, who played a younger version of Spock in last year’s “Star Trek” reboot. “He’s a terrific actor, he looks the part, and it’s time to give him some space. And I’m very flattered the character will continue.” Story continues below ?advertisement | your ad here Nimoy, 79, isn’t just done “Trekking” — he told the paper that his role on TV’s “Fringe” is finished as well. “I was away from acting for 12 years, so I guess I was seducible,” he said of his part as Dr. William Bell on the FOX show. “But since (producer) J.J. Abrams revived the ‘Star Trek’ franchise, I felt I owed him something. And I’m glad I did it because he promised me a good story, and it was.” Now, he said, he’s ready to step away from acting entirely. “I’ve been doing this professionally for 60 years,” he said. “I love the idea of going out on a positive note. I’ve had a great, great time.”

And yeah this guy did a ton of work across many shows and films, he was also in the series called Fringe and did a darn good job in it.

Live long and prosper Mr. Spock!