Robert Hamilton Duff JP (5 August 1925 – 11 May 2006) was a New Zealand rugby union player and coach. A lock, Duff represented Canterbury at a provincial level, and was a member of the New Zealand national side, the All Blacks, from 1951 to 1956. He played 18 matches for the All Blacks, two of which were as captain, including 11 internationals. He later was coach of the All Blacks from 1972 to 1973.^[1]

Duff was elected as a member of the Lyttelton Borough Council, and served as deputy mayor for 12 years.^[1][2] He was also a justice of the peace—the youngest in the country at the time of his appointment—and between 1984 and 1994 served as a member of the New Zealand Racing Authority.^[1]