Leonard Nemoy, who played the original Spock also played an older version of himself in the most recent Star Trek movie, Star Trek which ties the beloved actors from the original series to the newest actors to play those characters.
Soon it becomes clear that McCoy has somehow altered the past, and Kirk and Spock must go through the Guardian at some point prior to McCoy's entry, locate him and prevent him from doing whatever it is that changes history.
The setting, the musicality and even the character choices as well as the frictions between Vulcans (long-treasured allies thanks to Mr. Spock) and the humans, created a real chasm of opinion between Star Trek fans.
Of course, they are forced to give up the brain, which is surgically returned to Spock, and the women are faced with the prospect of having to re-merge their lives with those of the other gender on the surface.
In the third feature film: Star Trek III: The Search for Spock, Kirk and his crew stole the limping and soon to be decommissioned Enterprise to rescue Saavik, the young Spock and David from the Genesis planet.
Because Vulcans live for hundreds of years, the Spock character was able to transcend the hundreds of years between the original series and Star Trek the Next Generation where he appears as Ambassador Spock.
It is worth noting that Mr. Spock was half-human, perhaps to make him more accessible and acceptable to a human audience in the 'sixties, perhaps to make dramatic hay out of his 'at home nowhere' situation.
In Star Trek: the Original Series, Spock formed a third of the triumverate of main characters with Kirk and the Doctor, and offset and counterbalanced the Doctor's emotional response to situations.
People just weren't ready for women in positions of command, they said, so Number One was demoted (to nurse!) and Science Officer Spock was promoted to second-in-command of the Starship Enterprise.
Eventually, the episode climax occurs when Spock and Captain Kirk enter into a duel to the death, but beforehand, McCoy injects Captain Kirk with a compound that simulates a condition like death.