Wolf

The Wolf is a character on Once Upon a Time. He makes his debut, and, so far only appearance, in the seventh episode of the first season.

Before the Curse
The Wolf is first seen in the Forest growling at the Huntsman. He says that it won't go hungry. It then later seen gone to a tavern with the Huntsman's companion and the other patrons stare cautiously at the animal. They gossip that the Huntsman is an animal who was raised by animals and cries over his kills. One man comes over and asks him why he cries, and the Huntsman says that an honorable man cries, and that animals are pure of heart, not selfish and self-serving. The wolf growls at the man, who prepares to attack it. The Huntsman kills him and takes on the others, who withdraw after a few seconds. Meanwhile, the Evil Queen watches him through a shard of glass, decides that he's perfect, and tells her men to bring the Huntsman to her.

The Huntsman enters the palace and refuses to give his real name to the Evil Queen. He explains that the wolves raised him and that his parents only gave birth to him, and she believes that he is a wolf rather than a sheep. She asks him to kill someone and the Huntsman wonders why he should.She offers him a place at her court as her Royal Huntsman, awash in luxury, and explains that she needs someone without compassion, someone who can carve a heart out and bringing it back to her. The Huntsman says that he can do that and tells the Evil Queen to outlaw the hunting of wolves in return. She promptly agrees and the Huntsman asks her who he is to kill. It is later reviewed that the person is the Evil Queen's step-daughter, Snow White. However, after reading Snow White's letter, he's touched, unable to kill her and let her go. (The Heart Is a Lonely Hunter)

During the Curse
In Storybrooke, the wolf appears to Sheriff Graham (the counterpart of the the Huntsman), trying to lead him to the vault in which Mayor Regina Mills kept his heart, which she stole from him in Fairytale Land. The wolf leads Graham and Emma Swan to the tomb of Regina's father and disappears; however, the pair are unable to locate the heart. ("The Heart Is a Lonely Hunter")

Trivia

 * A wolf is seen by Emma Swan in the road leading out of Storybrooke in "Pilot"; it causes her to crash into the Storybrooke sign. This wolf is not the same as the Huntsman's companion, and is likely just a normal wolf.
 * The Huntsman was raised by wolves and considers them to be his family. The Huntsman and the wolf are close companions. ("The Heart Is a Lonely Hunter")