“And that, boys, is why you should never go for looks alone!”
-- Arthur Weasley (GF8)
Veela are female humanoid magical beings that have the ability to drive men uncontrollably wild, especially when they ‘turn on’ their charm or perform the sensual dance for which they’re known (GF8, GF22).
Veela are described as looking like incredibly beautiful women, with moon-bright skin and white-gold hair that fans out behind them despite the absence of wind. They have the ability to hypnotise and mesmerise most men with their seductive dance, who will then try to impress them. However, when they are angry they morph into bird-like creatures with elongated, sharp bird faces and long scaly wings that sprout from their shoulders. In this form, they throw handfuls of fire at whoever has angered them (GF8).
Veela hair has magical properties and can be used in wand cores. Fleur Delacour's wand has a veela hair core, from the head of her own grandmother, making Fleur one quarter veela (GF22).
There are no male veela (JKR).
The veela are based on a number of sources that describe Eastern European nature spirits of legend:
"Vily" are Slovic fairies who can take the form of birds.
"Vilas," as they appear in Serbian legends, are "mountain nymphs, young and beautiful, clad in white, with long flowing hair. Their voices are said to resemble those of woodpeckers. They shoot, according to popular belief, deadly arrows at men, and sometimes carry off children..." (The Fairy Mythology by Thomas Keightley, 1878.)
The book A Field Guide to the Little People describes the Vily (singular: Vila) in detail. They are nature guardians, caring for the trees, streams, and flowers in their domains. They are extremely jealous of beautiful women. Their moods are as changeable as the weather and they can both cause and cure illnesses. A human who tarries too long in their territory may be shot dead with arrows or die suddenly from heart attack, lumbago, or by being buried under an avalanche. Vily have fair complexions and curly, reddish-brown hair which falls to their feet. They wear shimmering white clothing or coverings of green leaves. Interestingly, those born on Tuesday or Sunday can most easily see Vily.
Veela are fascinating, alluring, beautiful... But what are they? Are they beings or beats? Birds or women? Some sort of in-between?
It is possible that in creating veela, J.K. Rowling was inspired by the Sirens of Greek mythology. Sirens were believed to combine women and birds in various ways. They had the power to enchant men with their beautiful voice and music. However, once under their spell, the men would be led to their doom, typically through shipwreck or drowning (Wikipedia).
From the Web
"Veela" on the Harry Potter Wiki
“Vila" from the Wikipedia page "Supernatural Beings in Slavic Religion"