John Adam may refer to:

• John Adam (architect) (1721–1792), Scottish architect
• John Adam (administrator) (1779–1825), British administrator in India
• John Adam (legislator) (1860–?), Wisconsin populist legislator from Milwaukee
• John Adam (sailor), British sailor, won silver medal at 1908 Summer Olympics
• John A. Adam (born 1949), American reporter
• John Adam (rugby league) (born 1956), Australian rugby league player
• John Adam (actor) (born 1960s), Australian television and theatre actor
• John Adam (MP) for New Romney
• John Adam (hoax), the name given by Islamic militants to a U.S. soldier they claimed to have captured