Powerful noncorporeal beings of the planet Thasus who raised the castaway Charlie Evans and gave him extraordinary abilities.
The Thasians are a noncorporeal species native to the planet Thasus. They rarely show themselves to other species, but their abilities go far beyond those of humanoids, including the power to transform matter and to alter living beings at will.
In Charlie X, it emerged that the Thasians had taken in Charlie Evans, a human boy who survived a crash on Thasus, and given him great powers so that he could live there. When Charlie abused those powers aboard the Enterprise, a Thasian vessel arrived, reversed much of the harm he had caused and took him back with them despite his pleas to stay.