Skin-walker
Native American
(Yeenaeldooshi - "with it, he goes on all fours" - Navajo)
Facts
Usually described as naked, except for a coyote skin or wolf skin.
Described as being fast, impossible to catch and agile.
Sometimes transform into an animal to travel large distances or just to wreck havoc.
Wild animal hides are taboo, and rarely seen in Navajo culture, because of thier assosiation with Skin-walkers.
In some Navajo legends, they have the power to read human minds. Also have th ability to make any human or animal noise they want.
Cannot completely transform into the animal, usually has a slight flaw in its gait or movements that lets humans tell that it is not a true animal.
Gain power by killing a close relative, usually a sibling.
According to legend the only way to shoot one is to dip bullets into white ash.
Skin-Walker In Books
Kitty Takes A Holiday by Carrie Vaughn - There are two Skin-Walkers in this book who follow the old legends of killing your sibling to gain power.
Skinwalkers by Tony Hillerman - A Mystery Novel (#7 in the series) that is based around Skin-Walkers