Saint John may refer to:

Several Saints:

• John the Apostle, to whom the Gospel of John is attributed
• John the Evangelist, traditionally identified with the apostle, and to whom the books 1 John, 2 John, 3 John, and Revelation are attributed
• Saint John the Baptist
• John Chrysostom, Archbishop of Constantinople
• Saint John of Damascus, revered Father of the Church
• Saint John of God
• Saint John of the Cross, Spanish mystic
• John Baptist de la Salle, the patron saint of teachers (also known by his French name, Jean-Baptiste de la Salle)
• Saint John Sarkander , Moravian priest

Place names (including alternate spellings Saint Johns and Saint John's):

• Saint John, New Brunswick in Saint John County, New Brunswick
• Saint John (electoral district) federal electoral district in Canada.
• St. John, Indiana
• St. John, Kansas
• St. John, Maine
• St. John, Missouri
• St. John, North Dakota
• St. John, Washington
• Saint John, United States Virgin Islands
• Saint John parish, Antigua
• St. John River, eastern North America
• St. John's, Antigua and Barbuda
• St. Johns, Arizona, United States
• St. John's, Newfoundland and Labrador, Canada
• St. John's, London, England
• St. John's, South Yorkshire , England
• St John's Wood, London, England
• St. Johns County, Florida
• St. Johns, Michigan
• St. Johns, Illinois
• St. John's, Isle of Man
• Saint-Jean-sur-Richelieu, Quebec, Canada (formerly St. Johns and Fort St-Jean)
• St. Johns riding is a riding in North Winnipeg.

Other possible meanings:

• The Order_of_St._John
• Prester John, a legendary Christian ruler in Asia and/or Africa
• San Juan (Spanish) (disambiguation page of the various places named San Juan)
• Saint John's University
• Saint John's College (disambiguation page of the various colleges named St. John's)
• Saint John's Church/Temp (disambiguation page of the various churches named St. John's)
• Ian St John , Dr, a teacher at The Haberdashers' Aske's Boys' School.