The Earth colony, also called Colony Five, where Charlie Evans's only known relatives lived and to which the Enterprise was carrying him in 2266.
Colony Alpha 5 is the Enterprise's destination in the original series episode Charlie X. The cargo ship Antares transfers the teenage Charlie Evans, sole survivor of a crash on Thasus fourteen years earlier, to Kirk's ship so that he can be taken to his nearest relatives at the colony.
As Charlie's uncontrolled mental powers and adolescent temper become obvious, Kirk grows alarmed at what the boy might do among ordinary colonists and considers diverting. Charlie responds by seizing control of the ship to make sure it keeps its heading.
The voyage is never completed. The Thasians arrive to reclaim Charlie, judging that he cannot live safely among his own kind.