Slaver
The Slavers were the founders of an ancient alien empire, which was the master of all intelligent races in the Milky Way Galaxy about a billion years before the 23rd century. They went extinct during the Slaver war.

In 2269, a depiction possibly representing a Slaver was discovered in a stasis box that had been earlier found by Kzinti archaeologists on Kzin. If this was indeed a depiction of a Slaver, it was the first to be unearthed since the fall of the Slaver Empire. ()

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Background information 
The Slavers are borrowed from the Known Space universe depicted in the writings of Larry Niven, who wrote the episode  in which the species is featured. The Slavers parallel Niven's Thrintun species (sg. Thrint), who ruled the galaxy through telepathic mind control in the distant past. The depiction of a Slaver that Sulu and Spock found in "The Slaver Weapon" closely follows the physical description of the Thrintun in Niven's works.

A carnivorous species with an uncontrollable hunger and low intelligence, the Thrintun's dominance over other races was derived solely from "The Power"—their telepathic abilities—which turned any intelligent beings into slaves. About two billion years before Humans emerged, the Thrintun were nearly destroyed by one of their enslaved races, the Tnuctip. In reaction, the Slavers issued a galactic "Die!" command, causing every sentient being in the galaxy to kill itself in an event known as "Suicide Night".

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Species