After Charlie misused his powers and caused considerable trouble for the crew of the Enterprise, the Thasian appeared as a translucent, floating Human face. He described himself as "having taken (his) form from centuries ago", so that he might communicate with the crew. The Thasian undid all the harm done by Charlie, and transported Evans from the Enterprise to its own ship. (TOS: "Charlie X")
The Thasian was portrayed by Abraham Sofaer. He was described in the script as "Thasian" and in the end credits as "The Thasian".