AT: "mu" Template:Sidebar character Kelby was a Terran ensign in the ISS Enterprise's engineering crew.
In 2155 he escaped the Enterprise's destruction in a Tholian web via escape pod, and was assigned by Commander Tucker to help get the Defiant's warp engines back online. When engine components under his supervision began to disappear, Tucker told Kelby to find them, or he would tell Commander Archer that Kelby was the reason they did not yet have warp power. Kelby entered a junction in search of the components and was killed by the culprit, a Gorn named Slar. (ENT: "In a Mirror, Darkly, Part II")
The mirror version of Kelby was played by actor Derek Magyar, who also portrayed his prime reality counterpart.