Fred Offenhauser (1888-1973), was an automotive engineer and mechanic who designed the Offenhauser racing engine, nicknamed the "Offy", which dominated competition in the Indianapolis 500 race for decades.

Offenhauser began working in the shop of Harry Arminius Miller in 1913, when the state of the art double overhead cam, four valve per cylinder Peugeot Grand Prix car, an engine design which would be contemporary even today, won the Indianapolis 500. The next year, 1914, Bob Burma was campaigning the engine, but when World War I made it impossible to get parts, Miller's shop got the job of maintaining it. The design so impressed Miller and Offenhauser that they designed an engine on largely similar principles.

In 1917, Offenhauser designed and built Barney Oldfield's famous "Golden Submarine ".

In 1919, Leo Goossen joined Miller’s shop and Offenhauser became plant manager. When Miller's company went bankrupt in 1933, Offenhauser bought it and he and Goossen began to develop the engine, with great success, 24 victories in 27 years. Offenhauser himself was not frequently seen in Indianapolis. In 2001 he was inducted into the International Motorsports Hall of Fame.