Henry Humphrey Evans Lloyd (c.1718 – 19 June 1783) was a Welsh army officer and military writer. He fought for the French against the Austrians, the Jacobite forces of Charles Stuart against the British, the Austrians against the Prussians and the Prussians against the Austrians (during the same war), and the Russians against the Turks. He also undertook various diplomatic missions for Britain. His writings on military theory were studied by George Washington and George S. Patton, and were used by J. F. C. Fuller to espouse a science of war.