Big John may refer to:

• John Baker (defensive lineman, born 1935) (1935-2007), American National Football League player
• John Cannady (1923–2002), American National Football League player
• John Huard (born 1944), American former National Football League and Canadian Football League player and coach, member of the College Football Hall of Fame
• John Kissell (1923-1992), American National Football League and All-America Football Conference player
• John Macklin (c. 1884–1949), American college football player, multi-sport head coach and athletics administrator
• Big John Mazmanian (1926–2006), American drag racer
• John McCarthy (referee) (born 1962), former referee for the Ultimate Fighting Championship (UFC)
• John Merritt (1926–1983), American football coach
• John R. Richards (1875–1947), American college football player, coach, educator and public administrator
• John Sears (racing driver) (1931-1999), American NASCAR driver
• Big John Studd (1948–1995), professional wrestler
• John Tate (boxer) (1955–1998), American boxer, WBA heavyweight champion (1979-1980)
• John Thompson (basketball) (1941–2020), American two-time NBA championship-winning player and NCAA championship-winning coach
• Jerry Tuite (1966–2003), American former pro wrestler

• Big John Bates, Canadian guitarist and singer
• Big John Duncan (born 1958), former guitarist for The Exploited
• John Goodison (musician) behind Big John's Rock And Roll Circus
• Big John Greer (1923–1972), American blues saxophonist and vocalist
• John Patton (musician) (1935–2002), jazz musician
• "Big" John Thomas, member of the Welsh hard rock band Budgie
• John Wallace (musician), bassist and singer
• Big John Wrencher (1923–1977), American blues harmonica player and singer

• John Buscema (1927-2002), American comic book artist
• John Castelle (born 1959), American mobster, a capo of the Lucchese crime family
• John Cornyn (born 1952), U.S. Senator from Texas
• John McMichael (1948-1987), Northern Ireland loyalist killed by the Provisional IRA
• John Fisher (social media personality) (born 1973), English social media personality
• Giovanni "Big John" Ormento, gangster involved in the French Connection
• Big John, bodyguard of rocker Bret Michaels who appeared on Rock of Love with Bret Michaels (season 1)

• "Big John (Ain't You Gonna Marry Me)", a 1961 song by The Shirelles
• "Big John", a working title of the ABBA song "Move On"
• "Big Bad John", country song by Jimmy Dean
• Big John, Little John, 1976 American TV series
• "Big John" Cannon, protagonist of the American TV series The High Chaparral

• Big John Bay, Kupreanof Island, Alaska
• A nickname for the John Hancock Center in Chicago, Illinois
• Big John Butte, a mountain in Montana

• Big John (brand), Japanese denim company
• Big John Steak & Onion, a sub chain based in Michigan
• A nickname of the US aircraft carrier USS John F. Kennedy (CV-67)
• Big John (dinosaur), fossilized triceratops

• Jon Arthur, the host of the Saturday morning children's radio series Big Jon and Sparkie
• Little John (disambiguation)