The last survivors of the planet Zetar, existing as a swarm of glittering lights that sought to take over the body of Lieutenant Mira Romaine.
The Zetarians were the final survivors of the planet Zetar, whose life had been wiped out. They endured only as a collective life force without physical form, seen as a cloud of glittering lights able to cross space and enter the minds of living beings.
In The Lights of Zetar, the Zetarians struck the Memory Alpha archive, killing its staff, and then tried to take over the body of Lieutenant Mira Romaine aboard the Enterprise so that they could live again. They were driven out and destroyed when Romaine was placed in a pressure chamber.