Jonathan Moran

 was the commanding officer of the Drum. He was scorched by rocket engines and transformed into a ghost by Prentis.

His ghostly form stalked the crew throughout the night, following them to the Faraday cage, which prevented the ghosts from entering. However, when the Twelfth Doctor and Clara Oswald arrived, Moran and Prentis went after them, attacking them with weapons but ultimately retreating through a wall. When the "day mode" of the base flashed on, however, Moran and Prentis dissipated, allowing the crew to move freely throughout the base without being attacked.

When the base unexpectedly went into night mode again, Moran and Prentis drowned crewmember Richard Pritchard and converted him into a ghost.

They were later trapped in the Faraday cage as part of the Doctor's trap. The Doctor spoke with the ghosts, but ultimately ended up leaving the base with two of the crewmembers. (TV: Under the Lake)