Following the cancellation of the original Star Trek series, Nimoy immediately joined the cast of the spy series Mission: Impossible, which was seeking a replacement for Martin Landau. Nimoy was cast as an IMF agent who was an ex-magician/ make-up expert, "The Great Paris." He played the role from 1969 to 1971, on the fourth and fifth seasons of the show. (As noted by Patrick White in The Complete Mission: Impossible Dossier, Landau had been an early choice to play Spock.)Thanks, Wikipedia.
Here's the opening from the fifth season of Mission: Impossible, featuring Nimoy and a young Sam Elliott (turns out he wasn't born with a mustache):
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*Previously: How to make sunglasses that make it impossible for someone to photograph your face.
*Mission: Impossible TV seasons are about $25 at Amazon.