Samuel Wathen, M.D. (c. 1720–1787) was an English physician who practised in London during the Georgian era. He was the personal physician to Rev. John Wesley and may have served Queen Charlotte of England as a male midwife.
Samuel Wathen was born in 1719 or 1720, most probably in Stroud, Gloucestershire, to Jonathan Wathen, a wealthy clothier of Stroud, and his wife Sarah Watkins. He became a physician, and then as a young man in Bristol in 1737, he met the Rev. John Wesley, one of the founders of Methodism. He ultimately became Wesley's personal physician, and there are several mentions of Wathen in Wesley's journal. He was the elder brother of Jonathan Wathen (c.1728-1808), a well-known London surgeon.
Wathen was admitted to the King's College in Aberdeen, Scotland on the recommendation of Dr. Nicholas Munckley (c. 1721–1770), a physician at Guy's Hospital in London and a member of the Royal Society. He graduated as a doctor of medicine on 28 September 1752 and was admitted to the Royal College of Physicians on 30 September 1756, going on to become one of London's best-known physicians. In addition to being a surgeon and John Wesley's personal physician, he was also one of the physicians of the City of London Lying-in Hospital on City Road where he was a man-midwife extraordinary. He was also listed on the Royal Kalendar of 1766 as man-midwife to the Queen, which must have been Charlotte, wife of George III, and makes it likely that he attended the Queen when her sons, the future George IV and William IV were born.