Leonard Nimoy and Mr Spock are always being mentioned in The Big Bang Theory – so it was only fitting that the show paid a special tribute to the late Star Trek actor.

The star, who died aged 83 on February 27, had made a cameo on the US sitcom in 2011, after years of being hailed as a hero by characters Sheldon, Leonard, Howard and Raaj.

Creator Chuck Lorre paid a short but moving tribute to Nimoy at the end of last night’s episode, using the show’s vanity card – the still at the end of the credits that usually features the producer’s details.

It read: “The impact you had on our show and on our lives is everlasting.”

Nimoy appeared on the show in 2011, when Sheldon, played by Jim Parsons, found his Mr Spock doll was speaking to him.