A data ghost was a digital impression of a living consciousness that sometimes remained in the neural relay of a 51st century communications systems after its occupant had died. It was very disturbing to observe a data ghost; Donna Noble called it the most horrible thing she had ever experienced. A data ghost would communicate through the speaker on the suits, horrifying the witnesses to their death. Three of Mr Lux's exploration crew experienced the data ghost phenomenon on their deaths in the Library: Miss Evangelista, Proper Dave (TV: Silence in the Library) and Other Dave.