John Monahan
John Monahan may refer to:
- John Monahan (scientist), Irish-born biochemist and CEO
 - John Monahan (law professor), professor at the University of Virginia Law School
 - John Monahan (RAF officer), English-born Royal Air Force officer
 - F. John Monahan (born 1943), American politician in Massachusetts
 - John P. Monahan (born 1932), United States Marine Corps general
 
See also
- John Moynihan (died 2002), American sports broadcaster