Corporal Kelly was a Human male who served as a Military Assault Command Operations soldier during the mid-22nd century. In 2153, Kelly was assigned to the MACO detachment aboard Enterprise NX-01 for the mission in the Delphic Expanse. After Enterprise returned to Earth in 2154, Kelly remained aboard as part of the MACO detachment.
In September of 2153, Kelly was one of the MACOs who accompanied Lieutenant Malcolm Reed and J. Hayes on a mission to the Xindi trellium mining planet to rescue Captain Jonathan Archer, Commander Charles Tucker III and Kessick. (ENT: "The Xindi")
Kelly and fellow MACO's S. Money and W. Woods were part of the away team which landed on the planet on which Humans and Skagarans settled down. Several cowboys and their leader Deputy Bennings opened the fire and the MACO's defended the away team including T'Pol, Captain Archer, and Lieutenant Reed. (ENT: "North Star")
Kelly guarded main engineering at the order of Captain Archer who was under the influence of Xindi-Insectoids. When the senior officers, including T'Pol and Malcolm Reed, tried to retake control over Enterprise, they overwhelmed the MACO's and stunned Kelly. (ENT: "Hatchery")
When the heavily damaged Enterprise drifted in space, Captain Archer decided to take what the ship needs by force and beamed an away team onto an Illyrian starship. While Archer's MACO force tried to divert the Illyrians, Commander Tucker and Corporal Kelly had to face a force field but managed to break through and steal the Illyrian warp coil. (ENT: "Damage")
The very next day, he was one of crewmembers who assisted in repelling a Sphere-Builder boarding party trying to stop Enterprise from destroying Sphere 41. Kelly reported over com that their weapons are passing right through the sphere builders and was ordered by Archer to take the power back because he needed a few more minutes. (ENT: "Zero Hour")
Kelly was portrayed by stunt actor Kevin Derr, who received no credit for his appearances. Although he wore the name tag E. Hamboyan in several episodes, he was referred to as Kelly in dialogue in the same episodes. Hamboyan was portrayed by background actor Andrew MacBeth. Derr also portrayed MACO G. Austin in the episode "Rajiin" and the Mirror universe counterpart Kelly. Kelly's voice in "Zero Hour" was performed by an unknown actor.
The novel Beneath the Raptor's Wing gives him the first name Matthew.