A skinwalker is a person and/or creature that possesses the ability to transform into any animal they desire. The Navajo skinwalker is known as 'yee naaldlooshii' and is a variety of Navajo witch. It is apparently far more common for men to be skinwalkers, though it is possible for women as well.
Skinwalkers are most frequently seen as coyotes, wolves, foxes, eagles, owls or crows and are not creatures to be trusted. Some Navajo believe that skinwalkers have the ability to steal the face of a person, and some believe that if one ever locks eyes with a skinwalker they can absorb themselves into a person's body, or that one's body might freeze up with fear, allowing a skinwalker to channel that fear to gain power and energy.
There are many other horrific tales about things that skinwalkers perform on their victims, such as using a poison powder of corpse dust made from ground infant bones (preferably the finger and skull bones of twin infants) to kill them with.
In some Native American legends, a skinwalker can transform into any animal by first wearing a pelt of the animal in order to properly transform into said animal. Similar lore can be found in cultures throughout the world and is often referred to as shapeshifting by anthropologists. Because it is believed that skinwalkers wear the skins of the animals they transform into, it is considered taboo to wear the pelt of any animal. In fact, the Navajo are only known to wear two hides, sheepskin and buckskin, both of which are only used for ceremonial purposes.
Another legend states that a skinwalker is, or was, a shaman in its human life. As a rite of passage, they kill their entire family to drain and absorb their souls. They then can transform into any animal they feels like, and any person. It has the ability to mimic voices that are familiar to a certain person, as a method of luring that person out.
Those who have talked of their encounters with these evil beings describe a number of ways in which a skinwalker will try to inflict harm. Some describe hearing knocks on the window or banging on the walls. Others have spotted an animal-like figure peering in through a window. According to Navajo skinwalker legend, they are seldom caught. Those who do track a skinwalker and learn of their true identity must pronounce the name of the evil one in full. Once this happens, the skinwalker will get sick or die for the wrongs they have inflicted against others.