The Dæmons were a race of powerful humanoids who profoundly affected Humankind.
Characteristics
Appearance
Dæmons are satyr-like humanoids with reddish skin and thick fur. They have sharp fangs, pointed ears, a thick beard and long horns. Their legs are goat-like with cloven hooves. They are around thirty feet tall naturally, but they can change their size with their technology. Dæmons have the ability to discharge bolts of electricity. (DW: The Dæmons) Some of this species, like the traditional picture of a demon, possessed long, forked tails. (DWM: Voyage to the End of the Universe)
Culture
The Dæmons had a horned god of evil. Though this may simply seem like a personified god, the Doctor surmises that it was actually inspired by the Beast. (DW: The Satan Pit)
The Doctor seemed to initially regard them as not evil, but coldly logical and amoral, without sentiment, which Azal's actions would bear out. (DW: The Dæmons).
However, they also seemed to organize according to the nuclear family structure and care for their mates and children. (DWM: Voyage to the End of the Universe) At a later stage of his life the Doctor had made the acquaintance of a friendly Dæmon known as Bonjaxx and attended a birthday party in honor of him. (DWM: Party Animals).
Powers
The Dæmons had technology indistinguishable from magic. They possessed matter-energy conversion technology which allows them to shrink and grow things at will. They used this to increase both their own size (which can range from microscopically small or to thirty feet tall) and to reduce the size of their ship in order to hide them. They also have the ability to set up heat force fields which can disintegrate anything that moves into it. They can also animate stone statues, as with the living gargoyle known as Bok.
A Dæmon could be psychically summoned by a special ritual, three of which were performed by the Master. The ceremony require negative emotions such as fear, which can be provided by frightened Humans. The more people that are involved and the more impressive the ritual, the more effective it is. Though these negative emotions can power the Dæmon, it also means positive emotions can be dangerous. A Dæmon will only appear three times to these rituals.
Azal offered his powers to the Doctor when the Master, who desired them, had proved himself unworthy. This would suggest that they can give their powers if they choose to. (DW: The Daemons)
History
The Dæmons were an ancient race from Dæmos (DW: The Daemons) who were powerful 150 million years ago. They were involved in the Millennium War and were one of the first species to strike back against the Mad Mind of Bophemeral stopping it from using a dark-matter cloud in the Rift of Perseus. (PDA: The Quantum Archangel)
The Dæmons studied he other races, treating the universe as their laboratory. (DW: The Daemons) Using a spacecraft, one Dæmon travelled to the edge of the physical universe, a feat achieved by few other beings. (DWM: Voyage to the End of the Universe)
By the 20th century all the Dæmons, save Azal, had died. (DW: The Daemons)
Effects on human development
Circa 100,000 years ago, they arrived on Earth, helped the Humans overcome the Neanderthals and then tried to lead their evolution and development. They are also known to have destroyed failed experiments, such as Atlantis.
The Dæmons inspired myths of gods and demons and the image of powerful beings with horns, including the Egyptian Khnum, as well as the Devil. (DW: The Daemons)
- Possibly they gave the Atlanteans the Kronos Crystal, which did indirectly cause the destruction of Atlantis, which seems not to have had any direct Dæmon involvement. (DW: The Time Monster)
Notes
Apart from the Dæmons, it seems that actual demons do exist.
Behind the Scenes
When the then-current production team of Doctor Who created the Dæmons for the story of the same name, they had no idea that later stories would introduce true demons into the Doctor Who Universe. Equally, the next year in the story The Time Monster they contradicted the scripts reference to the Dæmon having destroyed Atlantis, substituting a completely different explanation. Future writers would also portray the Dæmons as much more human and emotional.