After Charlie misused his powers and caused considerable trouble for the crew of the Enterprise, the Thasian appeared as a translucent, floating Human face. They described themself as "having taken (their) form from centuries ago", so that they 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. They were described in the script as "Thasian" and in the end credits as "The Thasian".
The alien character who appears at the end of "Charlie X" was originally to have taken the appearance of an elderly woman. In a memo that Associate Producer Robert Justman wrote Producer Gene Roddenberry (on 15 April1966, while the episode had the working title "Charlie Is God"), Justman commented, "Insofar as the old woman goes, I would like to get into that with you a little further, because I believe that this character should be the boy's father."