Fairy
Fairies (as the human race call them) are dangerous humanoid entities native to the Earth. Fairies are not alien life-forms, but have lived alongside humanity since they evolved. Their exact nature is unclear, although Jack Harkness describes them as part myth, part spirit world and part reality jumbled together, mixed with "old moments and emotions".
Powers and Abilities
Fairies have a wide variety of advanced, seemingly magical abilities. They have control over the elements, and are able to control the weather to produce localized, but deadly, storms and gales. Not bound by normal physical laws, they can choose whether or not a camera can take their pictures. For example, they made themselves invisible to closed circuit television cameras on one occasion. On another, they enabled themselves to have their photographs taken. They can travel through time and have an apparent non-linear relationship to it - as demonstrated by a picture of Jasmine Pierce, who became a fairy in 2007, in fairy form in 1917. A common method of killing their victims is to "steal their breath", asphyxiating them by clogging their throats with rose petals.
Fairies are seen in two forms: a small, glowing humanoid form with butterfly-like wings and a human-sized, more monstrous form. Both forms have wings and can fly with ease. At least in the larger form, Jack Harkness described them as only visible from the corner of one's eyes. (TW: Small Worlds)
Interactions with Humans
Jack said the Fairies came from the Dawn of Time. Humans, over time, made the fairies into something harmless and cute, however those who had encountered them (like Jack) never doubted their powers.
- Jack speculates that fairies may be "part Mara."
Apparently, Fairies were once human children, taken from various time periods stretching millennia into the past. Also, Fairies don't seem to reproduce normally, and instead take children and turn them into Fairies. These children are the Chosen Ones, who the Fairies protect and avenge if harm comes to them, until the time that they claim the children and take it to their "lost lands". These "Chosen Ones" always seem slightly odd and will try to spend as much time as possible with the Fairies. They generally aren't involved with the affairs of other humans, but they will violently defend any infringements on their territory and kill anyone who they feel has acted against them. (TW: Small Worlds)
They also can distinguish between who harmed the Chosen child and who didn't, as when Jack was on a train with a group of soldiers who had run over a Chosen One: the fairies attacked the men, but left Jack unharmed in a car full of dead bodies once they were done. The Fairies also appear to have limitless powers over the elements, as Jasmine Pierce, a Chosen One, told the team when they tried to stop her from being taken they would "Turn the world to ice". When Jack said that would mean no more Chosen Ones, Jasmine revealed the Fairies would simply keep to the past.
- It could be possible that Fairies don't reproduce because they are genderless. They speak in a soft, eerie and androgynous voice that makes it difficult to determine whether they are male or female.