Sir James Fellowes FRS FRSE FRCP (c.1771 - 30 December 1857, Langstone Cottage, near Havant, Hampshire) was a British military physician.
He was born in Edinburgh the third son of William Fellowes, physician-extraordinary to the prince regent - he was elder brother to the naval captain Thomas Fellowes. He was educated at Rugby School before spending time in the British Army's medical department, becoming surgeon's mate in June 1794. He then took his medical degree at Peterhouse College and Gonville and Caius College, along with London lectures from George Fordyce and Andrew Marshall and time in Edinburgh, finally graduating MD in 1803.
October 1795 saw him made physician to the forces, accompanying Admiral Christian's fleet to Santo Domingo and being sent to Gibraltar in 1804 to treat a contagious fever outbreak there. In April 1806 he came back to England, where in 1809 George III knighted him and appointed him chief of the medical department of the army at Cadiz, then in the midst of the Peninsular War. He then became deputy inspector (March 1813) then inspector (April 1813) of hospitals before retiring on half pay in 1814. Having been a first-hand eyewitness of epidemics at Cadiz, Málaga and Gibraltar, he then published Reports of the pestilential disorder of Andalusia, which appeared at Cadiz in the years 1800, 1804, 1810, and 1813 (1815). Arthur Wellesley appointed Fellowes deputy county lieutenant for Hampshire and Mrs Piozzi left Fellowes her manuscripts and copies of her writings with handwritten notes in 1821, with Fellowes becoming her literary executor.