Kevin Thomas Riley and his family lived at the Tarsus IV colony during the famine of 2246. Riley's parents were among the 4,000 colonists murdered by order of Governor Kodos. Riley was one of nine surviving witnesses to Kodos' order.

In 2266, Riley was a lieutenant, and served aboard the USS Enterprise. Early in the year, he served as a navigator. While on duty, he was intoxicated by the polywater infection brought back from Psi 2000, and became irrational. During this period, he took over engineering and regaled the crew with numerous offkey renditions of "I'll Take You Home Again, Kathleen". He also turned off the engines, causing the ship's orbit to spiral into the planet. "The Naked Time" Sometime after that incident Riley was transferred down to engineering.

Later in the year, the Enterprise ferried the Karidian Company of Players to Benecia. By this point, Riley had been promoted to the communications section. Kirk moved him back to engineering, to protect him from a killer who had already murdered one of the three remaining eyewitnesses. While he was there, Lenore Karidian attempted to poison him, and might have succeeded had he not been talking to off-duty personnel at the moment the poison took effect. Recovering in sickbay, Riley discovered that Anton Karidian was really Kodos the Executioner. Riley approached Karidian with murder on his mind, but James T. Kirk was able to talk him out of his vengeance.

Bruce Hyde (born 14 September 1941, is the actor who played Lieutenant Kevin T. Riley in the original series episodes "The Naked Time" and "The Conscience of the King".

He also had a recurring role during the fifth and final season of the TV series Dr. Kildare in early 1966. Overall, Hyde's on-screen acting career was quite brief, encompassing a grand total of nine TV guest appearances from November, 1965 to December, 1966.

Hyde is now the Chair of the Theater, Film Studies and Dance department at St. Cloud State University in St. Cloud, Minnesota.