People of Cheron whose skin is split into black and white halves, and whose hatred over which side is which led to their own extinction.
Cheronians have skin divided into black and white halves. On Cheron, those who were black on the right side considered themselves superior to those who were black on the left, and that difference shaped their entire society.
In Let That Be Your Last Battlefield, the Enterprise took aboard Lokai, a fugitive from Cheron, and then his pursuer Bele, who had chased him for fifty thousand years. Both possessed formidable mental power, and Bele used his will to seize control of the ship and force it toward Cheron.
When the Enterprise reached the planet, it found that the Cheronians had annihilated themselves in their hatred. Rather than accept that their war was over, Bele and Lokai beamed down to carry on their fight among the ruins.