The Teller (Time Heist)

The Teller was a large humanoid telepathic creature with an eye stalk on either side of its head. It was able to sense a human's guilt by scanning others' thoughts. It was also capable of emitting a form of energy that could liquefy the brain, causing the crown of the head to "cave in". It is possible that is how it feeds as Ms Delphox mentioned it was dinner time for the teller before it liquefied a costumer's brain.

It was one of only two of its species left alive, and was forced to work under Madame Karabraxos and her clone Ms Delphox at the Bank of Karabraxos, as the other surviving member of the species was held hostage. Just before the place was destroyed by a solar storm, when nearly everyone else had fled the bank, the Twelfth Doctor freed the imprisoned creature and dropped the reunited pair off together on a remote planet, far from civilisation so that the thoughts of other beings could not torture them. (TV: Time Heist)

Appearance
At the bank, the Teller was secured in an orange straitjacket whilst imprisoned, but when free of the straitjacket, the Teller had two long claws coming from the end of each arm, and a small ribbed tail-like protuberance. (TV: Time Heist)