Kooba

Keeba was a humanoid native of Trann Galaxy, and Laiko's second in command on his starship. After the ship had crash-landed on a planet in the Milky Way Galaxy, they began experimenting with an Age-ray machine to keep themselves from aging. After experimenting on crewmembers of the USS Enterprise, Keeba staged a mutiny and overthrew Laiko, using the Age-ray to enforce his command. He then attempted to overthrow the crew of the Enterprise and take their ship, but was thwarted by James T. Kirk, Spock, and Laiko, who managed to use the Age-ray against him, reducing him to childhood. He was left in that childish state.