A is for... Azal

A Daemon, from the planet Daemos. The Doctor described Azal as the last of the Daemons, but it is not clear if he meant the last of those who came to Earth, or the last of his race. Daemons visited primitive planets and helped them develop, purely out of scientific curiosity. These interventions were experiments. If found to be successful, the Daemons would bestow great powers on a ruler of the world. If deemed a failure, they would destroy. As part of Azal's mission, he brought about the rise of homo sapiens and the extinction of the neanderthals, and destroyed one of the Atlantean civilisations.
His influence was felt in the Renaissance and in the Industrial Revolution, even as he hibernated.
His ship was situated in the West of England, where it became buried within an ancient barrow monument. Daemons appear as horned beings, with cloven hooves, and their appearance had fed into myths and legends of horned entities throughout history - including the Devil. The barrow containing his spaceship was known as the Devil's Hump, and several place names in the vicinity had satanic origins.

When the Master learned of Azal's presence, he infiltrated the village of Devil's End as its new vicar and took charge of the local coven. Through this he sought to reawaken the Daemon, so that he could claim its psionic powers. Azal's return would be heralded three times. On the third he would awake. Daemons could shrink themselves or grow to enormous size - the process generating extreme cold or intense heat as mass and energy were converted. An incinerating heat barrier was placed around the village to keep out intruders during this process. The Master also harnessed his powers to animate a stone gargoyle - Bok - which could vapourise enemies.
When Azal did finally appear, he decided to pass on his powers to the Doctor instead of the Master. The Doctor only wanted him to leave and let humanity develop on its own. His refusal to accept the powers led Azal to kill him - but Jo Grant intervened. She offered her life in place of the Doctor's. Azal could not cope with such irrationality, and self-destructed.

Appearances: The Daemons (1972). Played by Stephen Thorne.

• There is an implication in the dialogue that Azal is not an organic being at all, but an avatar for some machine intelligence. As he dies he says that Jo's actions do not compute, and his spaceship explodes on his demise. He is also affected by the energy-draining machine which UNIT build to breach the heat-barrier. There are distinct similarities between Azal and the Malus - the Hakol psychic probe which appears in The Awakening.
• It has recently been confirmed that there are three paradoxical Atlantises, removing one of fandom's big continuity headaches, as on screen we have seen contradictory stories - two of them coming from the same authors only 12 months apart.
• It was originally intended that Azal would be voiced by another actor - Anthony Jackson. He was Fred Mumford in Rentaghost.
• One of director Christopher Barry's first decisions on joining this production was to change the name from Demons to Daemons, an archaic spelling.
• Azal's name derives from the fallen angel Azazel. It is from his legend that we get "scapegoat", as a goat would be sent out for sacrifice to protect the rest.