Cloud William was an inhabitant of the planet Omega IV.
In 2268, he was the leader of the Yangs and the guardian of the Holies, the speaker of the Holy Words, which are a version of the Constitution of the United States of America. The Yangs were are war with the Kohms, who were being helped by Captain Ronald Tracey in violation of the Prime Directive.
After attempting to kill Enterprise Captain James T. Kirk when they were imprisoned together, Cloud William would become Kirk's ally and help stop Tracey from interfering in the planet's politics. (TOS: "The Omega Glory")