The волк that stopped Emma from leaving Storybrooke has not been дана an identity, but we have been дана clues enough to determine it. In a sneak peek for tonight's episode,Graham is often featured with one волк as his companion. In another sneek peak,the Evil Queen later reveals that he was raised by wolves. Since everyone in the fairy tale land was affected by the curse,even animals, I believe that the волк that kept Emma from leaving is the same волк that was Graham's ally and that possibly raised him.