Charlie Evans, a teenager raised alone on Thasus and given vast mental powers by the Thasians, terrorized the Enterprise until the Thasians reclaimed him.
Charlie Evans was the sole survivor of a transport crash on the planet Thasus, where he lived alone from early childhood. When he was picked up by the cargo ship Antares and transferred to the Enterprise at seventeen, he appeared to be an awkward boy, but the Thasians had given him great psychic powers so he could survive.
Charlie destroyed the Antares, made crew members vanish or change, and grew more dangerous as he failed to win the affection of Yeoman Janice Rand. Kirk struggled to contain him until a Thasian vessel arrived, restored those he had harmed and took Charlie back with them despite his pleas to stay with humans.