Pixies come from Celtic mythology. Now they're often like Tinkerbell, with green outfits and caps and pointed ears, but the name may have come from the Pictic tribes who tattooed blue all over their skin. Pixies were sometimes seen as helpful, the queen of pixies was good luck, and they would sometimes turn into piles of rags to lure children into playing with them. Since the letter P also reminds me of Pratchett, I have to mention that the Wee Free Men sometimes call themselves Pictsies, and I will love them forever and always. Crivens!