Harry Arminius Miller (1875-1943) was an American mechanic who ran a race car shop that built and repaired race cars for the Indianapolis 500 race. After repairing the 1913 Peugeot Grand Prix car which was the state of the art at the time, Miller and his employee Fred Offenhauser designed the similar Miller racing engine which was to dominate Indianapolis for decades. After Miller went bankrupt, Offenhauser purchased the shop and continued development of the engine as the Offenhauser or "Offy" engine, which continued to dominate Indianapolis.