Star Trek: 10 Starfleet Officers Who Betrayed The Federation

10. Seska

Seska is an example of someone who only wore the uniform as a disguise - she never had any intention of being loyal to Starfleet. In fact, she was forced into the position of wearing the uniform while also in the process of betraying the Maquis. Seska was a Cardassian operative, surgically altered to look like a Bajoran.

Seska had been assigned to infiltrate Chakotay's Maquis cell and report back to Cardassian Central Command. However, no one counted on the displacement wave send by the Caretaker, enveloping their ship, the Val Jean, and flinging them across the galaxy to the Delta Quadrant. It could very well have been a trip into doom, had the USS Voyager not been caught in the same situation.

Seska then began to bide her time, slotting into the Starfleet crew, while eagerly searching for a way home. She slipped up when it was revealed that she had traded technology with the Kazon, causing an accident that led the trail right back to her. She was confronted by Janeway and Chakotay, where not only was her treachery revealed, but also her true Cardassian DNA. She smirked at the pair as she transported away, and would remain a thorn in their side for the next couple of years, until finally overreaching in the takeover of Voyager.