John Leech

John Leech may refer to:
 * John Leech (jurist) (fl. 1330s), English medieval professor of canon law
 * John Leech (caricaturist) (1817–1864), English caricaturist and illustrator
 * John Henry Leech (1862–1900), British entomologist
 * John Leech (mathematician) (1926–1992), British mathematician, discoverer of the Leech Lattice
 * John Leech (politician) (born 1971), British Liberal Democrat Councillor in Manchester and former Member of Parliament