Ominous hallway

This is the second floor office wing of the science building where I work. You may notice how well kept-up it is, the floors clean and shiny — our custodians do an excellent job. But notice the line of ceiling lights marching off into the distance, with their bright reflections in the shiny floor, one aligned with each office door…except one. One office sits in a pool of relative darkness. One where the lights don’t shine, where the resident lurks in perpetual gloom.

Can you guess who dwells there, in room 2390? Who has crouched there in the room haunted by gloaming murk for years?