Keniclius 5

Keniclius 5 was the primary antagonist of the Star Trek: The Animated Series episode "The Infinite Vulcan." He was a gigantic human who wished to bring peace to the galaxy by creating a master race.

Backstory
Keniclius 5 originated as Dr. Stavos Keniclius, a scientist from the Eugenics War era of late 20th-century Earth. The original Keniclius conceived of a master race cloned from a "perfect specimen," but was ostracised by the scientific community and left Earth, in much the same way that Khan Noonien Singh was forced into exile.

After several years of travelling, Keniclius crash-landed on Phylos, a planet populated by a civilization of plant-based lifeforms who wished to bring peace to the galaxy by conquering it. Keniclius, on realising that they had common goals, used a Phylosian process to clone himself into a gigantic new being named Keniclius 2, with all the memories of his former self. However, an unexpected complication arose when microbes aboard his spacecraft created a disease which wiped out most of the Phylosian population. Keniclius 2 eventually cured the plague, and was hailed as a master and savior by the Phylosians, but it proved a major setback to their plans, and left the long-term future of the Phylosian race in doubt.

As the years passed and his bodies aged, Keniclius cloned himself several more times, and was on his fifth body by the time the USS Enterprise arrived at the planet in the mid-23rd century. On seeing the Vulcan science officer of the Enterprise, Spock, Keniclius 5 determined that he had finally found the specimen he was looking for, and abducted Spock, threatening Captain Kirk and the rest of the landing party with dire consequences if they failed to leave.

By the time Kirk and his landing party managed to find their way to his lab, Keniclius 5 had succeeding in creating an equally gigantic clone of Spock, named Spock 2. Because the cloning process killed the original person, however, the original Spock was on the brink of death. Eventually, Kirk succeeded in breaking through to Spock 2, who used a mind-meld to help his counterpart recover.

Though the original Spock's life was now saved, Keniclius 5 and the Phylosians remained determined to carry out their plan to bring peace to the galaxy, by making more copies of Spock 2. Kirk was eventually able to talk them down by pointing out that the Federation was already bringing peace to the galaxy, and that they would be better joining it and helping them that way. At the end of the episode, Keniclius 5 and Spock 2 agreed to work together to try and fully restore the Phylosian race, who by now were in danger of dying out due to their limited numbers.