The Thasian ship was a space-faring vessel utilized by the non-corporeal Thasians. Apparently energy-based, the ship took on the appearance of an indistinct, green mass of light.

In 2266, this ship intercepted the starship USS Enterprise to retrieve Charlie Evans, a young man whom they had given their psychokinetic abilities, and take him back to their home world of Thasus due to the danger Charlie posed to others. (TOS: "Charlie X")