Maria Miller is Tommy's wife and the leader of the settlement in Jackson, Wyoming. You meet her at the hydroelectric dam in Tommy's Dam, where she first holds Joel and Ellie at gunpoint before learning Joel is her brother-in-law.
Maria and two of her people stop Joel and Ellie at the dam gate, guns raised, until Tommy recognizes his brother. She apologizes, surprises Joel with the news that she is married to Tommy, and invites the pair to eat. While the brothers talk, Maria eats with Ellie, tells her about Joel's daughter Sarah and shows her a photo of the two of them. Ellie quietly keeps the photo.
When bandits storm the dam, Maria and Ellie are barricaded in the dining hall until Joel and Tommy fight through and clear them out.
Once Tommy tells her he has agreed to take Ellie to the Fireflies, Maria is furious. She points out how many widows the settlement already has and tells Joel that if anything happens to Tommy, it is on him. Ellie overhears, which is part of why she runs away to the ranch house. Joel later admits to Tommy that Maria scares him a little.
Buckley
Buckley is the dog at Tommy's hydroelectric dam in Jackson County. You meet him in Tommy's Dam outside the generator building as Tommy walks Joel to his office, and Joel can stop to pet him.
Seth
Seth is a Jackson resident on guard duty at the hydroelectric dam in Tommy's Dam. He is the man beside Tommy on the wall, rifle trained on Joel and Ellie, when they first reach the gate.
Tommy Miller
Tommy Miller is Joel's younger brother, a former Firefly who now helps run the settlement at Jackson, Wyoming. He drives Joel and Sarah through the chaos of the prologue, and twenty years later Joel tracks him down at a hydroelectric dam in the chapter Tommy's Dam, hoping he will take Ellie to the Fireflies.
Callus
Callus is the horse Joel and Ellie ride from Jackson County to the University of Eastern Colorado and beyond. He first carries Joel when Ellie runs off in Tommy's Dam, and Ellie names him on the road to the university.