Kelly was a male Human Starfleet crewman who lived during the mid-23rd century. He served in the operations division aboard the USS Enterprise under Captain James T. Kirk, as one of the ship's security guards.

In 2267, Kelly served on a security team ordered by Lieutenant Commander Giotto to hunt for the Horta on Janus VI. He was scouting on his own when the mother Horta attacked him. By the time help arrived, he had been completely dissolved by acid. (TOS: "The Devil in the Dark")

This redshirt was played by Jon Cavett.
Kelly's name was not spoken on screen, but rather comes from both the 22 December 1966 and the 16 January 1967 revisions of the final draft of the episode's script; a reference that also appears in the Star Trek Concordance.