John Crosthwaite (9 October 1925 – 5 September 2010) was an English race car designer and engineer, active in both the United Kingdom and the United States. Crosthwaite worked with Cooper Cars, Colin Chapman at Team Lotus and Mickey Thompson as well as drivers Graham Hill, Dan Gurney and Jackie Stewart. He designed and built cars for Formula Junior and the 1962 and 1963 Indianapolis 500. A chassis specialist, he worked at Formula 1 team BRM and later drew up chassis for the Intermeccanica Italia, the Bond Bug and the Reliant Scimitar GTE road cars.