John Brett may refer to:

• John Brett (artist) (1831–1902), British artist associated with the Pre-Raphaelite movement
• John Brett (MP) for Much Wenlock
• John Brett (chronicler) (fl. 1556), English author of Brett's Narrative, about the Marian exiles
• John Brett (bishop) (died 1756), bishop of Elphin
• John Brett (Royal Navy officer) (died 1785), Royal Navy admiral
• John Aloysius Brett (1879–1955), administrator in British India
• John Michael Brett, nom de plume of English author Miles Tripp (1923–2000)
• John Watkins Brett (1805–1863), English telegraphic engineer
• John Henry Brett (1835–1920), Irish architect, builder, and county surveyor

• Jack Brett (1917–1982), British motorcycle racer
• All pages with titles containing John Brett