Wargs are people with the ability to enter the minds of animals and perceive the world through their senses and even control their actions.
According to Jojen Reed, the ability starts out as vivid dreams in which a warg sees and perceives the world through the senses of a wolf. However, he says that over time and with training a warg can enter the mind of a wolf at will.
Known Wargs
In the books
In the A Song of Ice and Fire books a "skinchanger" is a person with the ability to enter the mind of an animal and control its actions and perceive the world through their eyes. A "warg" is a skinchanger that does so with wolves. The TV series somewhat inaccuratey describes Orell as a "warg" even when he is controlling an eagle. The act of skinchanging is known as "warging".
Skinchanging seems to be limited to people who are blood of the First Men, i.e. the Free Folk and the Northerners.
See also
- Skinchanger at A Wiki of Ice and Fire (MAJOR spoilers from the books)