FitzJohn was a bus manufacturer in Muskegon, Michigan, United States.
FitzJohn, Fitzjohn, Fitz-John, or Fitz John may also refer to:
- Modern surname
- Medieval patronymic
- Children of John fitzRichard, one of William the Conqueror's supporters; including:
- Roger FitzJohn (died 1248/1249), Lord of Clavering, Warkworth and Horsford; son of John FitzRobert and Ada de Baillol
- Children of John Fitzgeoffrey (1205?–1258) Lord of Shere and Justiciar of Ireland; including:
- William FitzJohn (died 1326) Archbishop of Cashel and Lord Chancellor of Ireland.
- Thomas FitzJohn (died 1328), 2nd Earl of Kildare, Lord Offaly
- The 1st, 7th, and 9th Knight of Kerry
- John Fitz-John, Archdeacon of Totnes
- Walter Blake fitz John (died 1508), Bishop of Clonmacnoise, Ireland
- Dominick Lynch fitz John, Mayor (1548–9) of Galway, Ireland
- Given name
- Fitz John Porter (1822–1901) United States Army officer and a Union general during the American Civil War
- Fitz-John Winthrop (1637–1707), governor of the Colony of Connecticut