Kodos was the governor of Tarsus IV who ordered the deaths of thousands of colonists during a famine and later hid as a travelling actor.
Kodos was the governor of the Earth colony on Tarsus IV. When a fungus destroyed most of the colony's food supply, he seized power and ordered the execution of about four thousand colonists, choosing who would live based on his own ideas about who was most worthy. Relief arrived soon afterward, and a burned body thought to be his was found, so he was believed dead.
In fact Kodos survived and took on a new identity as Anton Karidian, leader of a travelling Shakespearean acting company. In The Conscience of the King, Kirk, who had witnessed the massacre as a boy, began to suspect Karidian's true identity as the few people who could recognize Kodos began to die. The killer was Karidian's daughter Lenore, who was trying to protect her father. When she tried to kill Kirk, Kodos stepped in front of the phaser blast and died.
Kodos tied Kirk's past to one of the darkest events in Federation history and showed how a person can hide from their crimes for decades.