President Barack Obama joined Leonard Nimoy's co-stars from "Star Trek" to bid adieu to the actor who died Friday aged 83 after making his name as "Mr Spock."

"Long before being nerdy was cool, there was Leonard Nimoy," said Obama, who recalled meeting the Boston-born Nimoy with the Vulcan salute in 2007.

More than a household name, Nimoy was a "lifelong lover of the arts and humanities, a supporter of the sciences, generous with his talent and his time," the president added.

"I loved Spock," said Obama.

William Shatner, who played Captain James T. Kirk on "Star Trek," was similarly effusive in his praise.

"I loved him like a brother. We will all miss his humor, his talent, and his capacity to love," Shatner said on Twitter and Facebook.

"RIP Leonard Nimoy. So many of us at NASA were inspired by Star Trek. Boldly go..." echoed the US space agency on Twitter, under a photo of the Star Trek cast visiting the space shuttle Enterprise in 1976.

"To boldly go where no man has gone before" was a catchphrase from the opening credits of the original Star Trek TV episodes.

- 'I will miss you' -

George Takei, 77, who played the helmsman of the Starship Enterprise on "Star Trek," told CNN how he and Nimoy had been good friends for half a century.

"When discussing a scene, he had a remarkable talent for analyzing the scene very quickly, in terms of its point, its drive," Takei recalled.

"But he was also able to guide other actors. He was really a company actor... A real leader and a brilliant actor."

Zachary Quinto, who played Spock in the two most recent Star Trek films, said he was heartbroken.

"I love you profoundly my dear friend and I will miss you everyday," he said on Instagram, alongside a portrait of Nimoy.

"Today we salute the legendary Leonard Nimoy #LiveLongAndProsper," tweeted the nerdy hit CBS sitcom "The Big Bang Theory," on which Nimoy once made a memorable cameo appearance, voicing a Spock doll.

Veteran Hollywood comedian Carl Reiner asked, via Twitter, if Spock "could not find a way to stay, what chance have we earthlings? 'May flights of angels sing him to his rest'."

"Leonard, you lived long and prospered, and were an inspiration to me and to millions. Rest in peace," tweeted Canadian astronaut Chris Hadfield, whose use of social media from the International Space Station helped reboot public interest in "the final frontier."