Prentice (imposter)

When ghosts started appearing all across Earth, one impersonated Jackie Tyler's deceased grandfather, Prentice.

He visited 48 Bucknall House whilst Rose Tyler and the Tenth Doctor were also visiting. He stayed until the end of the Ghost Shift, which only lasted a couple of minutes. "Prentice", along with all the other ghosts, were later revealed to be Cybermen. (TV: Army of Ghosts)