Fenric

Fenric, also known as Hastur the Unspeakable, Aboo-Fenrán, the Wolf and the Hunger, was an immensely powerful sentient force that was at least as old as theuniverse itself and an intelligence of pure evil, later identified as a Great Old One.

History
The being later known as Fenric was one of two forces, one good, one evil, which were present at the Dawn of Time and became caught in it. Somehow, the evil force survived. (TV: The Curse of Fenric)

The name Fenric came from a mythic figure in Norse mythology. The myths described a monstrous wolf which would, during the final battle between gods and beasts, destroy the world at the end of time. (TV: The Curse of Fenric)

Entrapment of Fenric
The Doctor's first known encounter with Fenric was in Constantinople in the middle of the 3rd century. Fenric (then known as Aboo-Fenrán) had been terrorising the area, when the prince El-Amjad tried to force him to leave. Fenric agreed, provided the prince gave him the first thing he named when he returned to his castle. El-Amjad agreed to this, but when the first thing El-Amjad named was his youngest daughter (due to the meddling of Fenric), he instead sent a chest of gold. When Fenric learned that El-Amjad would not give up his daughter, he continued to ravage the countryside.

Eventually, the Doctor arrived in the city, and agreed to help in exchange for freeing a slave called Zeleekhà. The Doctor went out to Fenric and challenged him to a game ofchess. After 40 days of stalemates, the Doctor was able to convince Fenric that with one move, he would win. Fenric spent another 40 days trying to figure out what this one move was, growing weaker all the time. Eventually, he became so weak that the Doctor was able to trap Fenric in a flask and banish him to the Shadow Dimensions.

Imprisonment
At some stage of Fenric's imprisonment, it briefly met and played a game of chess with the Celestial Toymaker. The Toymaker wished to claim Fenric as his new toy, while Fenric wished to take possession of the Toymaker's body so he could escape his prison. However, the game ended in a stalemate, and the Toymaker departed, leaving Fenric trapped.

Fenric's Stratagem
Fenric's power was such that his influence still continued to pervade space and time. He set into motion events that would ensure his escape.

Fenric summoned the Ancient One, the last Haemovore, from the future. WhenVikings stole the flask containing Fenric sometime after the 10th century, the Haemovore followed them and the flask to Northumbria and Maiden's Point. Fearing its evil influence, the Vikings buried the flask beneath St. Jude's Church, leaving arunic inscription warning that the flask was cursed. The Haemovore remained beneath the waters of Maiden's Bay, gradually recruiting new members. The Haemovores, also known as the Wolves of Fenric, awaited their master's release. (TV:The Curse of Fenric)

Still imprisoned, Fenric continued to manipulate the timeline in ways that would ensure his release. As she conducted a black magic ritual, Fenric used a time storm to whisk Lady Peinforte from her native time period of 1638 to 1988 to retrieve theNemesis statue. (TV: Silver Nemesis) He also transported Ace to Iceworld by time storm so that she could meet the Doctor and joined him on his travels. (TV: Dragonfire) As Ace bore the "curse", Fenric hoped that he could use Ace as a weapon against the Doctor. (TV: The Curse of Fenric)

Escape and Defeat
In 1943, Maiden's Point served as a the location of a military base housing theULTIMA, an early computer designed to decypher German code. The ULTIMA also had the secret purpose of translating the runic descriptions and so freeing Fenric. Once released, he occupied the body of Doctor Judson and had the Haemovores, already killing every human they could find, summon the Ancient One from his dormant state. Fenric later possessed Soviet Captain Sorin.

The Doctor attempted to trap Fenric once again using a game of chess, as before, but having taken over Sorin's body, Fenric had learned the solution to the chess puzzle. Fenric was finally defeated when the Ancient One turned on him, destroying Sorin's body and leaving Fenric without a corporeal host. (TV: The Curse of Fenric)