Jacob Black is a character from the Twilight book and movie series by Stephanie Meyer. He is introduced in the first book/movie as the son of a friend of Bella Swan's dad. He is a Quileute Native and is portrayed by Taylor Lautner in the films.
At first Jacob is the boy who crushes on Bella and is there for her after Edward abandons her. But he is much more than that. It turns out that Jacob's tribe believes they are descended from wolves, and unknown to most, some still possess the power to shapeshift.
When Jacob goes through his transition, he is sworn to secrecy and Bella must learn on her own what is going on. Jacob takes his place as leader of the pack and his strength of body and heart leads him to make great decisions concerning the truce between the wolves and the cold ones...