Captain Harris was a 23rd century Starfleet officer who served as the commanding officer of the Federation starship USS Excalibur during the late 2260s.

In 2268, Harris commanded the Excalibur during the disastrous M-5 Starfleet battle simulation war games in that year. When the M-5 malfunctioned in control of the USS Enterprise, commanded by James T. Kirk, it caused the Enterprise phasers to fire full-power on the other ships that participated in the games, severely damaging the unshielded Excalibur, Harris and the Excalibur first officer died early in the conflict, and all of his 400 or so crewmen were eventually lost.

The M-5 recorded, at Kirk's request, that no life remained aboard the hulk of Excalibur. (TOS: "The Ultimate Computer")