The family's founding patriarch was Judge Thomas Mellon (1813–1908), a son of Andrew Mellon and Rececca Wauchob who were Scotch-Irish farmers from Camp Hill Cottage, Lower Castletown, parish of Cappagh, County Tyrone, Ireland and emigrated to what is now the Pittsburgh suburb of north-central Westmoreland County, Pennsylvania. The family can be divided into four branches:
Thomas Mellon (1813–1908), Judge and founder of the Mellon Bank who married Sarah Jane Negley of Pittsburgh. As a boy he decided to abandon his parents' farming lifestyle for law and banking in the city after reading Benjamin Franklin's autobiography.
Matthew Taylor Mellon II (*1964) is the Chairman of the Republican Party Finance of New York, and is a Regent Director of Finance for the Republican National Committee. Mr. Mellon has founded or participated in multiple start ups such as Jimmy Choo, Harrys of London, Hanley Mellon, Marquis Jets, Arrival Aviation and Challenge Capital Partners. Mr. Mellon lives in New York with his wife Nicole Hanley Mellon and their son, Force. He also has a daughter, Araminta whom he raises jointly with his former wife Tamara Mellon.
James Ross (Jay) Mellon II (*1942) successful hunter and author of books about Abraham Lincoln, Slavery in America and his family’s founding patriarch, Thomas Mellon. According to an interview with the Swiss weekly newspaper, "SonntagsZeitung", he travels permanently in order to legally minimize taxes. He is married to Vivian Ruesch, daughter of Hans Ruesch.