Owen Richard Maddock (24 January 1925 – 19 July 2000) was a British engineer and racing car designer, who was chief designer for the Cooper Car Company between 1950 and 1963. During this time Maddock designed a string of successful racing cars, including the Formula One World Championship-winning Cooper T51 and T53 models.

The T51 was the first mid-engined car to win either the World Drivers' or Constructors' Championships, feats it achieved in the hands of Jack Brabham in 1959. A year earlier Stirling Moss had taken the first ever Formula One victory for a mid-engined car in another Maddock-designed vehicle: a Cooper T43. In addition to his Formula One work, Maddock also produced race-winning Formula Two, Formula Three and sportscar designs. After leaving Cooper in 1963 Maddock went on to a successful career as an engineering consultant, including a spell as a hovercraft designer working for Saunders-Roe on the Isle of Wight. In his spare time he also enjoyed racing hovercraft, and was a co-founder of the Hovercraft Club of Great Britain.

Away from engineering Maddock was an accomplished jazz musician. Among others, he was a part of Mick Mulligan's Magnolia Jazz Band, playing sousaphone, that featured George Melly on vocals. When the band decided to turn fully professional Maddock preferred to remain an amateur and left the group. He also counted saxophone, bass clarinet and piano among his repertoire, and continued to play and compete in jazz competitions until shortly before his death.

Owen Maddock was born in Sutton, Surrey, in January 1925. He was son of the architect Richard Maddock, who spent most of his life working for Sir Herbert Baker and was overseer for Baker's most controversial project in the United Kingdom: the rebuilding and destruction of large portions of Sir John Soane's Bank of England building in the City of London. Owen Maddock grew up in Sutton, and went on to study engineering at Kingston Technical College. During this time, in the latter years of World War II, Maddock also served in the local Home Guard regiment.

In addition to his engineering studies, Maddock was a proficient musician. He was able to play a number of instruments, eventually including trombone, saxophone, bass clarinet, piano, and sousaphone. He excelled as a jazz player and was part of many jazz bands of the late 1940s and early 1950s, including The Mike Daniels Band and Mick Mulligan's Magnolia Jazz Band. As a part of the Magnolia Jazz Band, Maddock played alongside vocalist George Melly. In his own memoirs Melly remembered Maddock as "a tall man with a beard and the abrupt manner of a Hebrew prophet who has just handed on the Lord's warning to a sinful generation ... and his hands, coat, clothes and face were always streaked with oil." Melly also recalled that Maddock could take his passion for jazz to extremes:

In his bedroom was an old-fashioned wind-up gramophone above which was suspended a weight through a pulley so adjusted as to lighten the pressure of the sound-arm on the record. On this antique machine he played Bechet records even while copulating. In fact the rather faded blonde with whom he was having an affair at that time told me she found it very disconcerting that, no matter what point they had reached, if the record finished, Owen would leap off and put on another.

— George Melly, Owning Up

On graduation he gained Associate Membership of the Institution of Mechanical Engineers, but his professional development was interrupted when he was called up for two years' National Service, during which he was stationed in Germany. After demobilisation Maddock went home to Surrey, and returned to Kingston Tech in April 1948 to complete a refresher course to maintain his AMIMechE status. As a part of this course he was required to spend eighteen months in a commercial workshop. At the time, Surrey was home to quite a few of the UK's smaller road and competition automobile manufacturers – including AC, Alta and HWM – and it was to the automobile industry that Maddock directed his attention.