Lokai was a renegade of the planet Cheron. He was white on the right side of his face and black on the left side, making him a member of his planet's minority ethnic group who were oppressed by the majority.
In the 2260s, he was hunted by Commissioner Bele. After their civilization eventually destroyed itself in 2268, both were the only survivors, left fighting on the ruins of their homeworld. (TOS episode: "Let That Be Your Last Battlefield")