Kathmandu, March 1: “I loved Spock,” said Mr Obama.
Nimoy died in Los Angeles on Friday. His son Adam said he died of end-stage chronic obstructive pulmonary disease, which is often caused by smoking.
His career took in acting, directing, writing and photography, but he was best known for portraying the half-human, half-Vulcan character Spock.
Obama said in a 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 time and talents.
“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.”
Obama’s approach to politics has been described as Spock-like. He greeted Nimoy with a four fingered Vulcan salute when the pair met in 2007.
Among the torrent of tributes on Twitter was a message from Nasa crediting Nimoy and Star Trek as an inspiration.
Other Star Trek cast members gave their praise too. William Shatner, who as Captain Kirk acted alongside Nimoy for years in Star Trek, said he loved the actor “like a brother”.
George Takei, who played Hikaru Sulu said “he was an extraordinarily talented man but he was also a very decent human being.”
Zachary Quinto, who played Spock in a Star Trek prequel, said: “My heart is broken.”
More than a Vulcan
Nimoy played the Spock in all three of the original series of the programme and later in several big-screen spin offs.
He did have success outside of his Spock costume, in both acting and directing, and he pursued music, painting, and photography.
After the end of Star Trek’s initial run, he played master of disguise Paris in the hit adventure series Mission Impossible.
Later he directed two of the Star Trek films, The Search for Spock and The Voyage Home, and in 1987 helmed the hit comedy Three Men and a Baby, one of the highest-grossing films of that year.