Yago

Warlord Yago was a leader of Argylus in the 23rd century, despite being merely a child. Like all the children of his world, he was intellectually (but not emotionally or physically) mature by age three.

In 2259, Argylus was stricken by a plague which killed everyone over the age of thirteen. The children built their own civilization with a feudal-looking appearance, complete with castles, warlords, kings and robotic knights, but were unable to find a cure to the plague. King Simon began transmitting a distress call in the hopes of bringing to his world a starship capable of curing them, but Yago had no hope that a cure would be found, and created games for his boys while they waited for death. However, he managed to co-exist peacefully with Simon.

In 2266, Yago and his boys captured Simon and a landing party from the USS Enterprise. He first demanded that they hand over the cure, then imprisoned them in the dungeon prior to their execution. During an escape attempt, Kirk discovered that their rifles merely fired harmless light beams and that this was just one of Yago's games. (TOS comic: "Child's Play")