John Farmer
John Farmer may refer to:
- John Farmer (composer) (c. 1570–c. 1601), Renaissance composer of madrigals
 - John Farmer (author) (1789–1838), American historian and genealogist
 - John Farmer (cartographer) (1798–1859), Detroit-based mapmaker
 - John Farmer (1835–1901) (1835–1901), music teacher at Harrow School
 - John Stephen Farmer (1854–1916), lexicographer and spiritualist
 - John Bretland Farmer (1865–1944), botanist
 - John Hind Farmer (1917–2012), SOE Agent, MI6 Agent
 - John Farmer (footballer) (born 1947), English footballer who played for Stoke City
 - John Farmer Jr. (born 1957), Attorney General, acting governor of New Jersey, and law school dean
 - John Q. Farmer (1823–1904), Minnesota politician and jurist