Sylph (also called sylphid) is a mythological creature in the Western tradition. The term originates in Paracelsus, who describes sylphs as invisible beings of the air, his elementals of air. There is no substantial mythos associated with them.
As alchemy in the West derived from Paracelsus, alchemists and related movements, such as Rosicrucianism, continued to speak of sylphs in their hermetic literature.
The first mainstream western discussion of sylphs comes with Alexander Pope. In Rape of the Lock, Pope satirizes French Rosicrucian and alchemical writings when he invents a theory to explain the sylph. In a parody of heroic poetry and the "dark" and "mysterious" literature of pseudo-science, and in particular the sometimes esoterically Classical heroic poetry of the 18th century in England and France, Pope pretends to have a new alchemy, in which the sylph is the mystically, chemically condensed humors of peevish women. In Pope's poem, women who are full of spleen and vanity turn into sylphs when they die because their spirits are too full of dark vapors to ascend to the skies. Belinda, the heroine of Pope's poem, is attended by a small army of sylphs, who foster her vanity and guard her beauty. This is a parody of Paracelsus, inasmuch as Pope imitates the earnest pseudo-science of alchemy to explain the seriousness with which vain women approach the dressing room. In a slight parody of the divine battle in John Milton's Paradise Lost, when the Baron of the poem attempts to cut a lock of Belinda's hair, the sylphs interpose their airy bodies between the blades of the scissors (to no effect whatever). The chief sylph in "The Rape of the Lock" has the same name as Prospero's servant in Shakespeare's The Tempest: Ariel.
Because of their association with the ballet La Sylphide, where sylphs are identified with fairies and the medieval legends of fairyland, as well as a confusion with other "airy spirits" (e.g. in William Shakespeare's A Midsummer Night's Dream), a slender girl may be referred to as a "sylph".
"Sylph" has passed into general language as a term for minor spirits, elementals, or faeries of the air. Fantasy authors will sometimes employ sylphs in their fiction.
In popular culture
In the Prefab Sprout song 'Desire as', Paddy McAloon describes 'desire as a sylph-figured creature who changes her mind'.
Sylphs feature in the Dungeons & Dragons role-playing game, as Air Elemental fairy-like creatures.
Sylphs are mentioned in the song "Thirteen Autumns and A Widow" from the band Cradle of Filth.
Sylphs are also present in Japanese video games, including Secret of Mana and the Tales series as well as Final Fantasy IV, V and Final Fantasy Tactics as summons. In Final Fantasy XII there exist various elemental creatures. The ultimate creature of the wind element is the Sylphi Entite.
The popular fantasy anime Record of Lodoss War features Sylph as the guardian wind spirit of the High Elf Deedlit.
In the Terry Goodkind novel series The Sword of Truth there is a magical being called the Sliph, which may be a reference to The Sylph.
The term also appears in the lyrics of Bal-Sagoth's Battle Magic
In Battletech, the Sylph is a battle armor that is capable of flight.
Willow, a Sylph, is one of the main characters in the Landover (Magic Kingdom) series of novels by Terry Brooks
In the manga Berserk, the sylphs appear as the main components of air.
In the open-source tactics game "Battle for Wesnoth" elvish sylphs are high-level magic units.
Sylphs feature in Everquest and Everquest 2 role-playing game, as Water and Air Nymph-like creatures; highly territorial and aggressive.
The Elemental Masters series by Mercedes Lackey features sylphs as lesser elementals, which may be commanded by Masters of that element. Sylphs in this series are depicted as flighty, mischievous creatures that nevertheless may cause devastating natural disasters, such as storms and tornadoes, when angered.
In Might and Magic VII, Sylphs appear as enemies.
In Digimon Adventure 02 two digimon named Gatomon and Aquilamon DNA digivolve to create Silphymon
The Saint Seiya character Basilisk Sylphid is portrayed as an antagonist, and uses techniques involving wind.
Thymilph, a character from the Tengen Toppa Gurren Lagann anime series, has his name formed from the combination of Sylph and the chemical component Thymine.
Sylph is a swift and powerful Wind-elemental character featured in a three-boss fight in the Squaresoft title Star Ocean: Till the End of Time
Jareth The Goblin King in Labyrinth (film) seems to possess many qualities of a sylph e.g. appearance (tall, lithe, with sharp and angular face) and and ability to shapeshift into a bird (a barn owl). Also note: "Wilder sylphs are intense and direct, like the birds of prey they resemble. They soar endlessly through the skies, looking for something to attract their interests and allow them to prove their worth" 
^ John Grant and John Clute, The Encyclopedia of Fantasy, "Elemental" p 313-4, ISBN 0-312-19869-8