President Barack Obama says Leonard Nimoy, who made the sign for "Live long and prosper" famous the world over, achieved that goal during his 83 years on the planet. 

The actor, who played Mr. Spock in the "Star Trek" TV series and films, died Friday at his Los Angeles home. 

Obama says he "loved Spock." 

Obama says Nimoy was there "long before being nerdy was cool." He described Spock as "cool, logical, big-eared and level-headed," and the center of an "optimistic, inclusive vision of humanity's future." 

He adds that he met Nimoy in person in 2007 and greeted him with the Vulcan salute -- four fingers separated into a "V" shape. 

Obama says he and first lady Michelle Obama join Nimoy's family, friends and fans in mourning his death.