- See Kelly for other articles with titles that contain, either by relationship or by coincidence, this character's surname.
In 2267, while on a landing party searching the tunnels of Janus VI for a killer alien that was later revealed to be a Horta, Kelly was killed when the mother Horta attacked him and sprayed him with deadly acid. (TOS episode: "The Devil in the Dark")
- Kelly, played by actor John Cavett, was not named in the episode, but in the Star Trek 4 novelization by James Blish, his character was referred to as Kelly, a reference that is likely derived from the original script, as the name also appears in the script-based reference book, the Star Trek Concordance. Kelly wore no rank insignia, so he was probably either an enlisted crewman or ensign, although this is not certain as some lieutenants also wore no sleeve insignia in TOS.