Nimoy, who had grappled with a love-hate relationship for his logical human-alien screen self, died Friday morning. His granddaughter confirmed Nimoy's death in a post to his Twitter account, @TheRealNimoy.
"Leonard Nimoy created a positive role model who inspired untold numbers of viewers to learn more about the universe. Many of those people are ardent space supporters and industry leaders today," Space Foundation Chief Executive Elliot Pulham said in a statement.
Last year, Nimoy disclosed on Twitter that he had been diagnosed with the progressive lung disease.
"I quit smoking 30 years ago. Not soon enough," he tweeted to his 810,000 followers. "Grandpa says, quit now!!"
Nimoy had other roles during a long career in TV, film and theater, and directed successful movies, wrote books, composed poetry, published photographs and recorded music. But he will be forever linked to the half-Vulcan, half-human Spock in the original 1960s "Star Trek" TV series and subsequent movies.
Known for suppressing his emotions and using strict logic to guide his actions, Spock became one of the best-known and most beloved sci-fi characters of the late 20th century.
For years, Nimoy resented that Spock defined him but ultimately came to accept that his life would be intertwined with the alien who inspired a fervent fan following for "Star Trek."
His feelings were summed up in the titles of his memoirs - "I Am Not Spock" in 1975 and "I Am Spock" two decades later.
"I was involved in something of a crusade to develop a reputation as an actor with some range," Nimoy wrote in "I Am Not Spock."
"I went through a definite identity crisis. The question was whether to embrace Mr. Spock or to fight the onslaught of public interest. I realize now that I really had no choice in the matter. Spock and 'Star Trek' were very much alive and there wasn't anything that I could do to change that."
Still, he wrote that if given the choice of being any other television character, he would choose Spock.
Nimoy had often confronted "Star Trek" creators during the original series over their conception of Spock, and his input was responsible for many aspects of the character.
He came up with the Vulcan nerve grip that rendered foes unconscious, as well as the split-fingered Vulcan "live long and prosper" salute, which he said was inspired by a gesture he had seen worshippers make in his synagogue when he was a boy.
Nimoy signed off his tweets with "LLAP," an abbreviation of Spock's trademark phrase "live long and prosper."
RELATIONSHIP WITH SHATNER
"Star Trek" followed the crew of the starship Enterprise as they explored other worlds and encountered aliens. Alongside William Shatner, who played Captain James T. Kirk, Spock helped make "Star Trek" a cultural phenomenon.
Shatner and Nimoy sometimes had a professional rivalry but maintained a long friendship.
"I loved him like a brother. We will all miss his humor, his talent, and his capacity to love," Shatner said in a statement.
The original series was canceled in 1969 by NBC after three seasons. But it found success during syndicated reruns in the 1970s and inspired fan conventions with hordes of devotees. It jumped to the big screen by the end of the decade.
Nimoy was not thrilled about taking part in the big-budget first film "Star Trek: The Motion Picture" in 1979.
But it was a financial success, leading to many sequels. Nimoy agreed to appear in "Star Trek II: The Wrath of Khan" in 1982 only after the producers promised him a great death scene and other sweeteners.
Even though Spock "dies" at the movie's end, Nimoy returned to play the character in the next four "Star Trek" films, directing the third and fourth ones.
After those efforts, Nimoy branched out and directed the comedy "3 Men and a Baby," the top money-making movie of 1987.
Spock, whose father was from the planet Vulcan and mother from Earth, served as first officer and science officer under Kirk. Vulcans looked human, except for their pointy ears.
In the successful 2009 "Star Trek" movie, Zachary Quinto took over the role of Spock but Nimoy appeared briefly as an older version of the character.
Nimoy, the son of Russian Jewish immigrants, was born in 1931 in Boston and began acting at age 8. In the 1950s and 1960s, he took a succession of roles on TV and in the movies, including "Zombies of the Stratosphere." Later he hosted the TV series "In Search Of..." (1976-1982) and co-starred in 1978's "Invasion of the Body Snatchers" film remake.
His everlasting renown as Spock led to quirky guest appearances on popular TV shows in recent decades, including the cartoons "The Simpsons" and "Futurama" (in which he provided the voice for his own disembodied head) and on the "The Big Bang Theory," in which he was the voice of an opinionated Spock doll.
Nimoy was married twice and had two children.