The Teller's Species

An unnamed race of telepaths which are extremely sensitive to the thoughts of other beings, and are able to establish mental connections strong enough even to unearth suppressed memories. At some point in time, this species was driven to near extinction, with only two individuals remaining.

Biology and society
Physically, they are strongly-built humanoids with dark greyish-brown skin, elongated fingers, a short tail, and a couple of long, flexible eyestalks projecting from each side of the head. Verbal communication among them appears to be either non-existent, or exists in a form that is not translatable by the TARDIS' telepathic circuits.

They are known to feed on the minds of other creatures, emitting energy waves which liquefy the victim's brain; even though the victims are still inexplicably alive afterwards. As intelligent beings, though, members of this race generally won't kill others unless they're being forced to by some circumstance.

It is heavily implied that they may have other forms of sustaining themselves without the need to kill, since they have no problem living on an uninhabited planet. Also, absorbing too much memories can be unpleasant for them, especially if the memories come from criminals and people plagued with guilt.

Appearances

 * Doctor Who, new series - S08E05 - "Time Heist" (2014)