Sir John Hayes, 1st Baronet

Sir John Macnamara Hayes, 1st Baronet (c.1750–1809) was a military physician.

Hayes was born in Limerick, Ireland. He was a British Army surgeon in the USA from 1775 to 1783. In the 1790s, he servewd in the army in the French Revolutionary Wars. In 1784, Hayes was appointed physician-extraordinary to the George, Prince of Wales, the future George IV of the United Kingdom. He was also a physician at the Westminster Hospital from 1792 to 1794.

For his medical service, he was awarded a baronetcy in 1797. In 1806, Hayes was appointed inspector-general of the ordnance medical department at Woolwich. This lasted until his death in 1809.