Chag Gara was a 23rd century Kyrosian man, a regional religious leader on the planet Kyros. Born around the year 2226, he was well known in the city of Andros as a rampant womanizer. He believed himself to be the sole messiah of the gods who lured followers in with promises of houris in the afterlife.
In 2269, he and Spock were mentally linked using a telescan cephalic implant which enabled Gara to use Spock's intellect to further his ambitions. The crew of the Enterprise recovered Spock from Gara and used radical therapy to "cure" him.