James "Jim" Hamilton (29 January 1918 – 6 July 2000) was an Irish mathematician and theoretical physicist who, whilst at Dublin Institute for Advanced Sciences (1941-1943), helped to develop the theory of cosmic-ray mesons with Walter Heitler and Hwan-Wu Peng. He was born in Sligo. His family moved to Belfast in 1920, where after attending the Royal Academical Institution he entered Queen's University in 1935. Following his graduation, Jim continued to work at Queen's, and was the first fellow to be enrolled in the School of Theoretical Physics at the Dublin Institute for Advanced Sciences.