Direwolf

Robb and Bran Stark find some direwolf cubs

A direwolf is an unusually large and intelligent species of wolf. A grey direwolf on a white field is the family symbol and crest of House Stark.

Range

Direwolves are held to be near-mythical in most of the south of Westeros, although there are rumors of them living in the Wolfswood near Winterfell. There have been confirmed sightings north of the Wall by the Night's Watch who guard it. The wildlings who live beyond the Wall claim that direwolves can be found in greater numbers in the Haunted Forest to the north of the Wall. When the series begins (during the reign of King Robert Baratheon) no direwolf has been sighted south of the Wall, even in the Stark lands of the North, in over 200 years.

Biology

An adult direwolf is as large as a small horse, and can rip a man's arm from its socket. Even a juvenile direwolf is quite capable of killing a man by ripping out his throat. Physically they are not simply larger versions of wolves, but have slightly different proportions from their smaller cousins: their head is larger with a more pronounced muzzle, their legs are longer, and they have proportionately more muscle mass than a similarly-sized normal wolf would.

List of direwolves in the series

The children of House Stark find six direwolf cubs at the very beginning of the series and adopt them. They are as follows:

• Grey Wind, adopted by Robb Stark. Currently with the Stark host at Riverrun, used by King Robb as a ferocious war dog. Killed durring the red wedding along with Robb Stark and has it's head attached to Robb's body.
• Lady, adopted by Sansa Stark. Lady is killed at the order of Robert Baratheon, at the urging of Joffrey Baratheon. Killed by Eddard Stark, remains brought back to Winterfell.
• Nymeria, adopted by Arya Stark. Fearing for Nymeria's life, Arya chased her away. She is now loose somewhere in the Riverlands, the first direwolf seen that far south (other than Grey Wind) in many centuries.
• Summer, adopted by Bran Stark. Currently with Bran at Winterfell. Untill Theon takes Winterfell for his own but can't hold it and is betrayed by Roose Bolton's bastard Ramsey Snow who keeps Theon as a sick twisted pet called Reek.
• Shaggydog, adopted by Rickon Stark. Currently with Rickon at Winterfell.
• Ghost, adopted by Jon Snow. Taken to the Wall with Jon.

Behind-the-scenes

Nymeria, a juvenile direwolf, portrayed by an adult dog in season one.

In season one, the production team used adult dogs to stand in for the juvenile direwolf puppies. In interviews they have stated that this was done to allow the audience to grow attached to them, which would have been more difficult had the dogs been created by special effects. However they have also stated that by season two, the direwolves will reach the point when they are too big to be represented by dogs, and will be portrayed as a CGI effect (i.e. a horse-sized Grey Wind ripping the throat out of Lannister war-horses, utterly terrified because they've never encountered a wolf bigger than themselves).