A. J. Watson (born May 8, 1924) was a car builder and chief mechanic from 1949 through 1984 in the Indianapolis 500, winning the race seven times, which leaves him tied for the record for most wins by a builder.
A native of southern California, Watson came to Indianapolis in 1948 but missed the race. He returned the following year with a home-built car that failed to qualify. For the next 11 years, his cars not only qualified but were leaders in many years. From 1955 to 1958 he was associated with the John Zink team, and from 1959 on with Bob Wilke. His cars dominated the race through 1964. Although he continued entering cars for another two decades, he was never able to regain the commanding position of his heyday.
In 1964, with many teams following Lotus's example and moving to rear-engined "funny cars", Watson built a pair of cars based on Rolla Vollstedt's successful car. These worked reasonably well but could not reproduce the success he had with his front-engined "roadsters". He built monocoque rear-engined cars in 1966 and 1967 with ever-decreasing success.
From 1969 until 1977, Watson ran Eagles and then built a small series of highly derivative new 'Watson' cars in 1977, 1978 and again in 1982 based on Lightning and March designs before retiring. He is frequently listed on the Indy 500 entry sheet as the "race strategist" for PDM Racing, though his role with the team is largely honorary.