John Harmon may refer to:
- John Harmon (coach), American football and basketball coach for the Boston University Terriers
- John Harmon (actor) (1905-1985), American actor
- John Harmon (attorney), U.S. Assistant Attorney General
- John Harmon Charles Bonté, lawyer and Secretary of the University of California
- John K. Harmon, radar astronomer at the Arecibo Observatory
- John H. Harmon, mayor of Detroit 1852-1853
- John Harmon, a character of Charles Dickens' novel Our Mutual Friend
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