10 Star Trek Characters Who Appeared On Multiple Series
6. Spock
There is an argument to be made that Spock is the most important Star Trek character ever created.
Originally played by Leonard Nimoy, Spock first appeared on The Original Series in 1966. As the Science Officer on the USS Enterprise, he was frequently the voice of reason in opposition to Captain Kirk's emotional brashness. But he was also Kirk's chief supporter, loyal advisor and closest friend.
But the end of The Original Series was by no means the end of the character. In addition to the movies, Spock went on to appear in two pivotal episodes of The Next Generation as did his father, Sarek. He appeared again in the new CBS All Access series, Discovery, but in a different reality than The Original Series and its spin offs. This version of Spock is far less self assured and confident than the original version.
While the character never pops up on Deep Space Nine, his presence is felt in the Mirror Universe episodes. They were continuations of The Original Series episode where four members of the Enterprise ended up in an alternate reality where the Federation was an evil oppressor. The Mirror Universe Spock changed his ways and that of his Federation, the repercussions of which were explored on DS9.