Jonathan Moran was the commanding officer of the Drum, an underwater mining facility in Scotland in 2119. While saving his friend Cass, Moran was scorched by rocket engines and transformed into a ghost by Albar Prentis.
His ghostly form stalked the crew throughout the night, following them to the base's Faraday cage, which prevented the ghosts from entering. They wandered for three days and waited patiently for the crew to leave the cage to collect supplies where they attacked them using chairs and knives, but their attempts were unsuccessful.
When the Twelfth Doctor and Clara Oswald arrived, Moran and Prentis went after them, attacking them with weapons but ultimately retreated 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, which they sent to attack Clara.
They were later trapped in the Faraday cage as part of the Doctor's trap. He tried to harm the Doctor but failed. The Doctor spoke with the ghosts, but then left them, enabling the ghosts to figure out a way to flood the base. (TV: Under the Lake)
When a holographic projection of a ghost Doctor arrived, it opened the Faraday cage and let the other ghosts out. Moran's ghost followed Cass, dragging an axe. It was just about to finish her off when Cass escaped.
The ghosts were later driven back into the Faraday cage by the roar of their master, the Fisher King. The Doctor told Clara that UNIT would cut out the Faraday cage and eject it into space where away from the Earth's magnetic field, the ghosts would dissipate. (TV: Before the Flood)
Behind the scenes
The ghost of Moran is used as an enemy in the Doctor Who: Legacy mobile game.