Doc Hudson is the doctor and judge of Radiator Springs and once a Piston Cup racer. He is mostly called just Doc. He is called "Grandpa" by Lightning sometimes. He was known as the Fabulous Hudson Hornet in the Piston Cup series when he won three Piston Cups in 1951, 1952, and 1953 and got out for the season after getting injured. He was Lightning's crew chief in the Los Angeles International Speedway. He taught him how to powerslide. As himself he is blue. As the Fabulous Hudson Hornet he is red, yellow, and blue and is number 51.