10 Most Fearsome Alien Races In Star Trek
9. Talosians
The Talosians were used sparingly in The Original Series, but their particular quirk was clever and original enough to leave quite the lasting impact. Their bulging foreheads and dashing cloaks give them an archetypal alien supergenius look, but their way of life and their methodology is particularly fiendish.
After a nuclear holocaust laid waste to their planet, the surviving Talosians, buried under the rubble, were forced to harness their psychic abilities (hence the big old heads). They learned to summon convincing illusions, which passed the time for a while, but soon became a little boring and predictable.
From there, their pleasure was derived from luring space travellers to their homeworld, where they would beguile the lost souls with their incredibly real conjurings.
The Talosians, it seemed, had no real malice to what they did, but could easily snap the brains of any of their human subjects. They end up assisting Spock et al in their reappearance later in The Original Series - but if they wanted to, they have the power to wipe out just about everyone through sheer mind trickery.