Elves

Elves were sometimes thought to be male faeries -- in England, this especially applied to small faery boys. In general, the term 'elf' in England referred to the smaller trooping faeries, although in Scotland, elves were human sized, and Faeryland was called 'Elfame.' 

In Scandanavia, faeries were also called elves, and were either light elves or dark elves, similar to the Scottish Seelie and Unseelie Courts. The light elves were like England's trooping faeries, and in Christian times, Scandanavian elves (or huldre folk) destroyed cattle, stole humans away, and avenged any injuries done to them in the same way that the Scottish faeries did. Huldre maidens dressed in grey with white veils, and were beautiful but had long cows' tails. If a man was dancing with a huldre girl and noticed her tail, he must not betray her, but instead tactfully mention that she was losing her garter. He would then be rewarded by perpetual prosperity. 

Danish elves loved to steal human food, such as dough. Though beautiful from the front, Danish elves or ellewomen were hollow from behind. 

Publications such as Goedys' Lady's Book, published by Louis A Goedy, popularised the idea of the Christmas elf in the nineteenth century, and JRR Tolkien's famous The Hobbit brought elves into high fantasy in the twentieth century. 

Bibliography: An Encyclopedia of Fairies, by Katharine Briggs.

Webography: Wikipedia: http://en.wikipedia.org/wiki/Elves.

Picture courtesy of Google Images: https://www.google.com/search?hl=en&site=imghp&tbm=isch&source=hp&biw=1024&bih=600&q=elf&oq=elf&gs_l=img.3..0l10.1727.1949.0.2324.3.3.0.0.0.0.112.264.2j1.3.0....0...1ac.1.24.img..0.3.264.r2OyC5CcxgE.