Charonians are humanoids who are bilaterally divided in coloration; on one side their skin is stark white, while on the other it is jet black.
Charonians seem to have similar physical attributes to humans, but they are able to manipulate matter and energy with their thoughts, allowing them to control the course of a starship by force of will, damage circuity with a gesture, shield themselves against phaser fire, and generate dangerous amounts of heat when grappling with other Charonians.
It is unclear when the Charonians developed their bilaterally divided coloration, but it became cause for racial prejudice based on which side of the Charonian's body was white and which was black. Charonians who were black on the right side became dominant and oppressed those who were white on the right side. The racial animosity eventually resulted in a civil war that destroyed the entire species.
With their inherent energy-manipulation abilities, the Charonians would be an extremely powerful faction if they weren't so obsessed with their own race war. As it is, they became extinct before they could become a significant interstellar power.