John Thornton - Buck’s final master, a gold hunter experienced in the ways of the Klondike. Thornton saves Buck from death at the hands of Hal, and Buck rewards Thornton with fierce loyalty. Thornton’s relationship to Buck is the ideal man-dog relationship: each guards the other’s back and is completely devoted to the other. The strength of their bond is enough to keep Buck from acting on the forces he feels are calling him into the wild.Buck - A powerful dog, half St. Bernard and half sheepdog, who is stolen from a California estate and sold as a sled dog in the Arctic. Buck gradually evolves from a pampered pet into a fierce, masterful animal, able to hold his own in the cruel, kill-or-be-killed world of the North. Though he loves his final master, John Thornton, he feels the wild calling him away from civilization and longs to reconnect with the primitive roots of his species.