Serosian
From Memory Alpha, the free Star Trek reference
The Serosians are a warp-capable species from the planet Seros in the Delta Quadrant.
Physically, the race are humanoid, although they have a pale, almost metallic cast to their skin. They use holographic technology and create sentient holograms to act as cleaners and maintenance personnel aboard their ships. Unfortunately these programs, referred to as isomorphs, are not well-treated by their creators.
In 2374 the USS Voyager received a distress call from a Serosian hologram called Dejaren. Although he claimed the crew of his ship had been killed by a virus, it later became apparent that his program had destabilized and he had become obsessed with cleanliness to the point of psychosis. As a result he had murdered the crew. (VOY: "Revulsion")
