The Starfleet officer who replaces Trip Tucker as chief engineer when Tucker transfers to the Columbia.
Commander Kelby joins Enterprise as chief engineer when Trip Tucker transfers to the Columbia in Affliction. Taking over a department Tucker built, he is soon tested when Klingon sabotage leaves the ship unable to slow below warp 5 in Divergence, and Tucker returns to resolve the crisis.
In Bound, Kelby falls under the influence of the Orion slave D'Nesh, whose pheromones heighten the aggression of the male crew, and he sabotages the warp drive before Tucker can stop him.
In Terra Prime, he is briefly suspected of sabotaging a shuttlepod before the real saboteur is identified. Kelby's struggles to fill Tucker's shoes, and the crew's readiness to doubt him, underline how important Tucker is to the ship. He was played by Derek Magyar.