She nearly succeeded in taking over the starship but, fortunately, her plan failed when Wesley Crusher learned the truth about what she was up to and was able to reactivate Data – who had been disabled before the game was widely dispersed throughout the ship as the only person who would have been immune to its effects – allowing Data to restore the crew to their normal selves and allowing them to capture her vessel. (TNG: "The Game")
According to the final draft of the script, Etana was "alien, gorgeous, with a full, flowing mane of hair;" additionally, the script was also the source of her last name, Jol.
During the episode she is never referred to as a Ktarian; indeed she only spoke of them in third person, but is clearly identified in reference materials, namely Star Trek: Aliens & Artifacts, as Ktarian. For more information on these discrepancies, see the full analysis at Ex Astris Scientia.