People of Ekos. Hear me. We were betrayed by a self-seeking adventurer who has led us all to the very brink of disaster. I order the immediate recall of the space fleet. This attack must stop. All units are to return to base. To Zeon I promise this was not an aggression of the Ekosian people, only one evil man. Melakon is a traitor to his own people and all that we stand for. To the Zeon people I promise reparation...
~ John Gill (stopping Melakon's genocidal crusade, shortly before he is killed by an enraged Melakon)
Melakon is a villain from Star Trek: The Original Series, a humanlike alien who was part of a Neo-Nazi regime formed by John Gill, a misguided Federation official and historian who believed that the philosophy could do good for society, despite its many flaws.
He was portrayed by Skip Homeier, who also played Rota Sevrin.
Melakon was not so keen on this attempt to soften Nazism, however, and decided to go down the same dark path that Hitler did on Earth - drugging Gill and effectively taking his place so as to try and orchestrate his own version of the Holocaust upon a neighboring world.
When Kirk and Spock aided Gill to expose Melakon as a usurper, he took to arms and killed Gill with a machine gun. Melakon was in turn shot in the stomach by an immigrant from the world he had sought to destroy, killing him.
While utterly ruthless and embodying the worst of Nazi philosophy, Melakon did not seem to be able to hold as much sway over his people as Hitler did and many of his own kind were considering rebelling against him even before he was exposed as a traitor; he was served by the equally savage Ekosian SS.
This is one of Star Trek 's more controversial episodes due to the Nazism themes - to the point that it had been banned in Germany for a number of years. Melakon himself was fashioned after Adolf Hitler and his genocidal crusade was based on the Final Solution (also known as the Holocaust, one of history's most infamous massacres)
Melakon likely suffered from the same megalomania, xenophobia and sociopathy that Hitler did or idolized the Nazi dictator to such an extent he began to see himself as Hitler.
Prior to Melakon's reign, the Ekosians under Gill were trying to use Nazism as a model to make a strong society, trying to remove the xenophobic elements of the regime; the idea of Nazi Germany being one of the most successful empires of all time was popular in the time period in which the episode was released but has since become a source of great debate by historians.
The topic of Nazi aliens returned, however, with Enterprise and introduced Vosk and his allies, who were aiding Earth's Nazi Germany thanks to time-travel.
The mirror universe version of Melakon served on the Terran Emperor's cabinet as Security Minister, and it was noted that he bore a striking resemblance to fellow cabinet member Rota Sevrin.