John Arnold may refer to:
Politicians
John Arnold (Kentucky politician), member of the Kentucky House of Representatives, 1995–2013
John Arnold (MP for Ipswich) (died 1410), MP for Ipswich, 1388–1399
John Arnold (MP for Hampshire) (died 1433), MP for Hampshire, 1413
John Arnold (MP for Monmouthshire) (died 1606), MP for Monmouthshire, 1597
John Arnold of Monmouthshire (c. 1635–1702), Ultra-Protestant and MP for Monmouth, 1680–1689, 1695 and Southwark, 1689–1695
John H. Arnold (politician) (1862–1944), American politician; Lieutenant Governor of Ohio, 1915–1917
John W. Arnold (1842–1900), American politician; Illinois Senate, 1890–1894
Music
John Arnold (1720–1792), English music editor and composer of psalmodies in the West Gallery style
John Dent Arnold (1890–1948), American lyricist with composer Harry Baisden of World War I songs
John Ayldon (1943–2013), English opera singer born John Arnold
Others
John Arnold (American football) (born 1955), American football player
John Arnold (bishop) (born 1953), English Catholic bishop
John Arnold (cinematographer) (1889–1964), American cinematographer
John Arnold (judge) (1915–2004), British judge
John Arnold (priest) (born 1933), Anglican dean and author
John Arnold (watchmaker) (1736–1799), English watchmaker and inventor, with a son named John Roger Arnold (1769–1843)
John D. Arnold (born 1974), former Enron trader and political activist
John E. Arnold (1913–1963), American psychologist and engineer
John H. Arnold (historian) (born 1969), British historian and professor
John Nelson Arnold (1834–1909), American portrait painter
Johnny Arnold (1907–1984), English international footballer and test cricketer
John Arnold, Australian surf entrepreneur, behind Golden Breed
John Arnold, perpetrator of the murder of Betty Gardner
John Arnold, a character in the novel Jurassic Park