Jeffrey Hammond (born 30 July 1946), often known by his former stage name Jeffrey Hammond-Hammond, is an artist and retired musician best known for being the bassist of progressive rock band Jethro Tull from 1971 to 1975. With Jethro Tull, Hammond played on some of the band's most successful and well-known albums, including Aqualung (1971) and Thick as a Brick (1972).
Hammond adopted the name "Hammond-Hammond" as a joke, since both his father's name and mother's maiden name were the same. He also joked in interviews that his mother defiantly chose to keep her maiden name, just like Eleanor Roosevelt.