Star Trek: 10 Disturbing Side Character Backstories
6. Kevin Riley
Kevin Riley was the unhinged Lieutenant who drunkenly took over the Enterprise's engineering section while the crew was affected by a ship-wide intoxication virus in the classic Original Series episode The Naked Time. He definitely stole the show here, and many fans may only remember him from this episode, but Kevin Riley actually appeared once more in the episode The Conscience Of The King, in which we learn some disturbing facts about his early life, as well as Kirk's.
Years before serving on the Enterprise, Kirk and Riley both lived on the planet Tarsus IV. Food shortages on the planet led their leader, Governor Kodos to pull a "Thanos" and kill half of the colony's 8,000 residents, according to his personal belief in eugenics. Kirk and Riley survived, but both of Riley's parents were selected to die.
In The Conscience Of The King, Kodos was found to be still alive, and Riley, desperate for revenge, tried to kill him with a phaser, but was eventually stopped by Kirk.