Tom is an alcoholic who encounters Frank Ross outside of a pub, intending to help the man while he was drunk. In a panic, Tom drew a firearm and shot Frank in cold blood before fleeing. Frank Ross is buried and Mattie Ross, his vengeful daughter, begins plotting the murderer's justice.
La Boeuf, a long time rival of Chaney, later explains that Chaney also encountered a Senator in Texas while he was in a park and shoots him dead. This murder had less influence than Frank Ross' and drew the attention of La Boeuf, who investigates the murder and hunts for Tom Chaney with no success. La Boeuf later learns of Frank Ross' murder and meets his daughter to aid in her manhunt alongside the hired marshal Rooster Cogburn.
To avoid the jurisdiction of the region, Tom begins living in native American territory and encounters the outlaw Ned Pepper and his gang, before he was recruited by them and began travelling with them to commit more crimes. The gang is poorly supplied and plots to collect more loot from nearby settlements, though Tom's allegiance with the gang is beginning to be questioned due to his apparent lack of responsibility.
One day, be begins washing the horses at a nearby stream, but is surprised to find and recognize Mattie Ross collecting water nearby. The pair exchange threats and insults with Tom being held at gun point, before the overly confident thug is shot in the rib when the gun misfires. Shocked but largely unhindered, Tom overpowers her and takes her back to the gang's camp. While Ned is busy warding of the two bounty hunters and the gang return to the camp, Tom threatens to brutalize the girl and have her thrown into a snake pit. Ned ensures her safety and demands Tom's cooperation, under threat of being unpaid for his work. Ned then leaves Mattie at the camp and charges Tom to remain and watch her, much to both parties reluctance.
Tom and Mattie share a conversation over the murders he has committed and the effects of his decisions on his life, before finally concluding that her 'silence' would benefit him. He begins strangling her to death before being knocked out by La Beouf, and the pair oversee the final confrontation between Ned's gang and Rooster. After shooting Ned with a rifle, La Beouf is bludgeoned from behind by Tom with a rock. Mattie and Tom struggle over the rifle before Mattie pulls it from his grip and cocks it. She orders him to stand and face his demise before she fires, shooting Tom in the chest and sending him plummeting down the cliff behind him.
Tom Chaney, despite having an intimidating presence, is seen to lack a level of competence in the times he is seen. He is noted by other characters to be slow witted, whilst also being praised for his cunning by others. He lacks loyalty towards others and is willing to sooner abandon any made allies than be forced into submission, even if it is to his own benefit.
He is also somewhat cowardly, as most times he is seen in conflict is either against person's incapable of retaliating or by attacking when the person least suspects it. He lacks any regard for other's lives and the misery he has left in his wake, and will sooner paint himself as sympathetic whether or not he or others believe he has earned it.
Tom Chaney has black short hair matched with a mustache and short beard, all of which is left unkempt to complement his untidy appearance. He is widely recognizable by his signature powder mark on his cheek.
He has a black undershirt along with a black coat reaching his hips. He has marching black pants and leather boots,
He is armed with a Sharpes repeater.