Bigby Wolf, also or formerly known as the Big Bad Wolf, is the sheriff of Fabletown. He has the duty of protecting the Fables from the mundies and themselves. He is the main protagonist of The Wolf Among Us.
Once upon a time:
Bigby was one of seven pups born to the North Wind and Winter. He was the runt of the litter and mockingly called the big, bad wolf by his brothers; Bigby for short. He hated his father for leaving his family. When Winter died, his brothers went to learn from the North Wind, but he stayed behind to try to protect Winter's body from scavengers.
After he failed to protect his mother's body from scavengers, he vowed to kill something bigger everyday. By the time he hunted the Three Little Pigs, he had discovered the gifts he inherited from the North Wind. The first humans he hunted were Red Riding Hood and her grandmother. A local woodsman was able to pull them out, sew rocks into his belly, and throw Bigby into a river. He survived by holding his breath for three weeks (another gift from the North Wind) and passing stones until he could swim to the surface. Following that incident, he swore to only hunt humans.
As Bigby began eating humans, he began to grow unnaturally large. He devoured entire towns, defeated armies, and even killed a dragon. Eventually, he made his way towards the North Wind. He tried to eat his father seven times and each time he was sent flying for seven times seven days. After the seventh time, he vowed to forget his father, stop mourning his mother, and be his own wolf.
When the Adversary's armies invaded, the Wolf discovered that the flesh of anyone serving in the Adversary's armies was tainted with a foul taste. Furious that the Adversary was stealing his usual prey without providing a suitable replacement, and refusing to join the Adversary's army himself (determined not to follow any master but himself), he dedicated himself to thwarting the Adversary's plans. He traveled from kingdom to kingdom.
He eventually came to a certain kingdom, where he learned of a witch who had a portal to the mundane world. When the witch traveled through the portal herself, the Wolf followed her and marked the trail, so that he and only he would be able to find the portal again. In furtherance of his attempts to frustrate the Adversary, the Wolf took up the task of leading fables who wished to escape the Adversary through the portal. In order to ensure that no spies were shown through, he insisted on tasting the flesh of everyone to whom he showed the path, and determining whether it was tainted or not. In this way he first encountered Snow White and Rose Red, who had been captured by the Adversary. On meeting Snow White for the first time, he noticed her pleasant scent (which is apparently, to a wolf, a sign of one's future mate), which he would never be able to forget. When the Wolf had killed the group's goblin captors, most of the captives attempted to flee the Wolf in terror, except for Snow White and Rose Red, who could not move because of their chains. Snow White took up a sword to defend herself, which the Wolf found particularly amusing. Freeing them, he offered to take them through the portal if they would let him taste their flesh, which they did.