The Celtic peoples have many references to fairies in their myths and legends, and their nature is described in widely different ways. They are also known as 'the little folk', but this can also refer to leprechauns, goblins, menehune, and other mythical creatures. (full apologies to believers). In Ireland, the fairies were known as the Sidhe, and in Scotland, the Daoine Sith, or a great many variant names.
The height of fairies was not always as consistent as is held to be the case today. Traditionally, faeries were often of human height or taller. One consistent belief amongst the Britons was that the fairy people were weak against cold iron, leading to many of the iron related superstitions that have existed, some of which survive to this day. (For instance, the tradition of placing a horse shoe on one's door.) This belief has prompted some historians and mythological commentators to speculate that the fairies are actually derived from a folk memory of the people that inhabited the island of Great Britain before the Celts arrived. These people would have been armed only with stone, and hence iron would have been the decisive Celtic advantage.
In contemporary belief, fairies are often characterised as fundamentally benevolent in demeanour; this does not, however, hold true in many historical manifestations. The belief in changeling children, for instance, where the fairies would steal away a mortal child and replace it with one of their own, was widespread in mediaeval times; this motif appears in the folk-songs Thomas the Rhymer and Tam Lin, among others.
William Shakespeare's play A Midsummer Night's Dream deals extensively with the subject of fairy-folk and their interaction with a group of amateur theatrical players. This work details the spell cast by the mischievous fairy Puck (at the behest of the fairy-king Oberon) on Oberon's wife Titania, who falls in love with the first mortal she casts eyes upon, the unfortunate Bottom, whom Puck has transmogrified into having a donkey's head.
William S. Gilbert liked fairies and wrote several plays about them. The best is the Gilbert and Sullivan operetta Iolanthe which deals with a conflict between fairies and the House of Lords and, among other issues, touches on some of the practical consequences of fairy/human marriages and cross-breeding in a humorous manner.
Conversely, the Victorian painter Richard Dadd was responsible for some paintings of fairy-folk with an altogether more sinister and malign nature. The Victorians in Britain were much taken with the notion of fairies in the wake of the Cottingley fairies photographs, and a number of artists turned to painting fairy themes. Another notable Victorian painter of fairies was the artist and illustrator Arthur Rackham.