Tom Paris

Tom Paris was a Starfleet officer who was imprisoned for terrorist activity before being allowed to assist the crew of the USS Voyager in a mission to track down a terrorist ship. Paris was aboard the ship when they were flung into the Delta Quadrant and was awarded the rank of Lieutenant for his bravery in saving many members of the crew from death. Following this he became friends with Harry Kim and made it his mission to find the guy a girlfriend.

Paris was well-respected by Kathryn Janeway as he knew the workings of the ship inside and out. This allowed him to perform tricky maneuvers with the ship that would be otherwise impossible, making him a valuable member of the crew despite his dodgy past.