John Nielsen

• John Nielsen (footballer, [born 1911)]
• John Nielsen (footballer, born 1946), Danish player
• John Nielsen (footballer, born 1972), Danish player
• John Nielsen (racing driver), Danish auto racer
• John M. Nielson, American minister in the Church of the Nazarene
• John Nielsen, American nature writer and NPR science reporter, see National Outdoor Book Award#Natural [history literature|National Outdoor Book Award]