Thursday night’s episode ended with a black-and-white portrait of Nimoy with the words, “The impact you had on our show and on our lives is everlasting.”
Leonard Nimoy and his character, Mr. Spock, were in a way secondary "characters" on The Big Bang Theory with the number of references on them throughout the series.
Sheldon, played by Jim Parsons, has a real connection with Leonard Nimoy. In one particular episode, Sheldon receives a gift of a lifetime — well, his anyway — a napkin used by the Star Trek actor.
“I possess the DNA of Leonard Nimoy?!” Sheldon exclaims in the episode.
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Leonard Nimoy even made a cameo on the show during its fifth season.