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.
When Ellie rides away from the dam, Joel takes this horse to chase her to the ranch house at Hidden Pines Corral. The two keep him for the trip to find the Fireflies.
Callus waits outside the science building while Joel and Ellie search it. A man tries to steal him, and the pair use him to get away from the campus.
While Joel lies wounded at the Colorado Mountain Plaza, Callus stays with him. His noise draws the hostile survivors who followed them from the university, and Ellie has to fight them off. Callus then carries both of them to Silver Lake, where they shelter for the winter.
Ellie ties him to a tree while she tracks a deer, and rides him again the next day to lead a search party away from Joel.
During the chase in Lakeside Resort, the cannibals shoot Callus and he falls from a ledge, leaving Ellie distraught. David later taunts her that his group will eat the horse.
Lakeside ResortLakeside Resort jumps to winter and puts you in control of Ellie near Silver Lake, Colorado, hunting with a bow and searching for medicine. She runs into two strangers, David and James, and for part of the second half the game switches you back to Joel.Joel Miller
Joel Miller is the man you play for almost all of The Last of Us Part I. A hardened smuggler in the Boston quarantine zone, he takes a job escorting 14-year-old Ellie out of the city, and the drop-off turns into a year-long trip across the country to find the Fireflies.
Ellie Williams
Ellie Williams is the 14-year-old girl Joel is hired to smuggle out of Boston, and your companion for most of The Last of Us Part I. She was bitten weeks earlier and never turned, so the Fireflies believe her immunity could lead to a vaccine. You play as her in the winter chapter and in the Left Behind DLC.
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.
Maria Miller
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.