Buck
The protagonist of our story, Buck is part St. Bernard, part Scotch shepherd. At the beginning of the story, Buck is a domesticated, but atypical dog who lives in the home of Judge Miller in California. After being kidnapped and taken to Alaska to become a sled-dog, Buck's wild nature is reawakened, and he slowly returns to the ways of his ancestors.
Spitz
An experienced and clever Husky, Spitz is the original lead dog of Buck's dogsled team. He fears and hates Buck, whom he sees as a rival. He is eventually killed by Buck in a fight for leadership.
Curly
A sweet Newfoundland dog, one of Buck's first companions after he has been kidnapped. She is unexpected killed for trying to make friendly advances toward another dog.
Dave
Another one of Buck's first companions, he is one of the most knowledgeable dogs on the team. Mostly aloof, new life springs into him the moment he is placed in a harness. Not only does he help teach Buck the procedures, he also embodies pride in his work.
Sol-leks
Another member of the team. Like Dave, he is aloof until attached to a sled. At first only wary of being approached on his blind-side, poor treatment makes Sol-Leks more and more unfriendly.
Billie
Another member of the team. He is good-natured and sweet, and he shows Buck how to make a bed in the snow. He is killed by Hal.
Joe
Another member of the team, Billie's brother. Unlike Billie, Joe is always snarling and defensive.
Pike
Another member of the team, often referred to as "the malingerer." He rarely gets up on time, and he will steal food and generally undermine the expedition. When Buck becomes leader, he forces Pike to shape up and become a helpful member of the team.
Dub
Another member of the team. He is an awkward blunderer who gets blamed for Buck's thievery.
Dolly
Another member of the team, Dolly goes mad after being bitten by wild huskies, tries to attack Buck, and is killed by Francois.
Skeet
A motherly Irish setter who belongs to John Thornton. She nurses Buck through his recovery and engages him in play.
Nig
A huge black dog who belongs to John Thornton. He has laughing eyes and a good nature.
Lone wolf
The "wild brother" that Buck meets in the forest. He understands Buck's wild nature.
Judge Miller
Buck's original owner. He is presumably a sedate and prosperous man with a large family.
Manuel
The gardener's helper on Judge Miller's estate. He kidnaps and sells Buck to fund his gambling habit.
Red sweater
Also known as the man with the club. He metes out discipline to all dogs that will be sold for sledding. Ruthless in his repeated beatings of unruly creatures such as Buck, he maintains composure and control. He does not beat out of cruelty, it seems. Rather, he looks to teach these dogs the lessons that will allow them to survive in this harsh environment. Buck never forgets the law of the club.
Francois
A Canadian Frenchman, the original dogsled driver. He is knowledgeable and understanding of his dogs, but still very strict.
Perrault
Francois's superior and an agent of the Canadian government. He is admired by Buck for his fearlessness in blazing their trail, disregarding the threat of ice that might break.
Hal
A young man of nineteen or twenty who purchases Buck and his team once they have used up their usefulness to the government. He has ambitions to find gold, but his incompetence and laziness are out of place in the harsh environment. He has no understanding of the dogs, and mistreats them terribly.
Charles
Hal's brother-in-law, a weak figure who does not say much. He basically follows Hal around and does what he is told.
Mercedes
Sister of Hal, wife of Charles. She is exceedingly self-centered, and spends most of her time crying and complaining.
John Thornton
The man who rescues Buck from Hal's cruelty. He is by far the most admirable human character in the story, kind but full of the uncompromising strength that is necessary to survive on the trail. John is the ideal master because his nature is so dog-like.
Pete
One of John Thornton's partners.
Hans
One of John Thornton's partners.
"Black" Burton
A notorious troublemaker, he picks a fight in a bar and John Thornton steps in.
Matthewson
The man who bets John that Buck cannot pull a ton of weight.
Jim O'Brien
The man who loans John the money to make the bet against Matthewson.
Yeehats
The group of Valley Indians that raids the camp of John Thornton and his companions and kills them. They are terrorized when Buck returns and kills most of them. From then on they speak of a dog inhabited by the devil that roams the forest.