"doctor — Who" Heaven Sent(2015)

: A creature manifested from the Doctor's childhood nightmares. It only moves when the Doctor is not looking or when he stops confessing.

: Delivers a tour-de-force performance, essentially carrying the episode alone. He uses a "Mind Palace" version of the TARDIS to process his thoughts and solve the puzzle of the castle. "Doctor Who" Heaven Sent(2015)

: Appears only as a manifestation of the Doctor's imagination, providing the motivation he needs to keep fighting through the cycle. Cultural Impact & Critical Reception : A creature manifested from the Doctor's childhood

: It was nominated for the Hugo Award for Best Dramatic Presentation (Short Form) . He uses a "Mind Palace" version of the

The episode received universal acclaim and remains a high-water mark for the series:

Following the death of Clara Oswald, the Doctor is teleported into a remote, shifting castle surrounded by a vast ocean. He is pursued by a slow-moving, hooded creature known as , which is designed to scare him into confessing his deepest secrets.

: Frequently tops fan polls, including being voted the #1 all-time favorite story by readers of Doctor Who Magazine .