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