WASHINGTON -- U.S. 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 centre 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.

Here is Obama's full statement:

Long before being nerdy was cool, there was Leonard Nimoy. Leonard was a lifelong lover of the arts and humanities, a supporter of the sciences, generous with his talent and his time. And of course, Leonard was Spock. Cool, logical, big-eared and level-headed, the centre of Star Trek’s optimistic, inclusive vision of humanity’s future.

I loved Spock.

In 2007, I had the chance to meet Leonard in person. It was only logical to greet him with the Vulcan salute, the universal sign for “Live long and prosper.” And after 83 years on this planet -- and on his visits to many others -- it’s clear Leonard Nimoy did just that. Michelle and I join his family, friends, and countless fans who miss him so dearly today.