Puck is a mischievous nature sprite in English folklore who has inspired a number of figures, including the spirit of the same name in Shakespeare's A Midsummer Night's Dream. Puck is so closely associated with mischief and fun-loving personalities that the term “puckish” is sometimes used to describe someone with an independent streak and a love of practical jokes.
Stories about fun-loving sprites and spirits are common to many world religions, and some form of Puck has probably existed in the folklore of the British Isles for centuries. This figure is also sometimes known as Hob or Will-o-the-wisp, and in A Midsummer Night's Dream, he also goes by “Robin Goodfellow.” These variable names reflect Puck's constantly metamorphosing personality.
While Shakespeare depicts Puck as a single, distinctive individual, originally the term “puck” was used to describe any sort of mischief-loving nature spirit. These spirits supposedly appeared in all sorts of guises to confuse people and play pranks on them. For example, one might appear to lost wayfarers, using lights and strange sounds to guide them even further astray.
Puck also supposedly loves playing pranks around the farm, causing farm animals to become restless and doing things like souring the milk and spoiling the eggs. Historically, some people used various charms and symbols to ward Puck off, regarding his pranks as nuisances which could potentially be quite damaging. Spoiling the milk, for example, could cause a farmer to lose a day's worth of work or more, which could be a problem for a farmer depending on dairy products to make a living.
Puck is variously described as a tree spirit, a nature spirit, or a poltergeist. Probably, legends about Puck emerged in an attempt to explain strange happenings and events which seemed to defy rational and logical explanation, much as poltergeists and ghosts are used today. Not being a god, Puck would not have been worshiped, but people probably paid their respects to him nonetheless, to avoid being pranked or inconvenienced by him.
Thanks to Shakespeare, Puck is a well-known mythological figure, and as a result, he is often referenced in pop culture, fantasy novels, and so forth. Puck often appears in retellings of British mythology in particular, and some authors have even turned him into a complex and well-developed character with distinct goals and thoughts beyond basic troublemaking.