John Clay may refer to:

• John Clay (Wars of the Roses), English soldier
• John Clay (chaplain) (1796–1858), English prison chaplain
• John Clay (cricketer, born 1924) (1924–2011), English cricketer
• John Clay (offensive tackle) (born 1964), American football player
• John Clay (running back) (born 1988), American football player
• John Cecil Clay (1875–1930), American illustrator
• John Granby Clay (1766–1846), British general
• John Morrison Clay (1821–1887), American horse breeder
• John P. Clay (1934–2013), investment banker and founder of the Clay Sanskrit Library
• John Randolph Clay (1808–1885), American diplomat
• Johnnie Clay (1898–1973), English cricketer
• The Red-Headed League, an 1891 short story by Arthur Conan Doyle with a character named John Clay

• Jon Clay (born 1963), British former track and road racing cyclist