Richard Pritchard
Richard Pritchard was the representative of Vector Petroleum on board the Drum, an underwater mining facility in Scotland.
When commanding officer Jonathan Moran was killed, Pritchard took charge. When the Doctor arrived and raised awareness about a missing power container from a discovered spaceship, Pritchard made it his mission to find it.
Later, when he had come back from exploring the lake, he was met by Moran's ghost, who drowned him. Clara and Mason Bennett saw his body floating out in the water, but then were met by his ghost, which attacked them but was repelled by the light.
Later, the Doctor led the ghosts into the base's Faraday cage, trapping them with the intention of discovering what they were all muttering in unison. After the Doctor left, the ghosts figured out a way to flood the base. (TV: Under the Lake)