| Most Reverend Geoffrey Mayne | |
| Honorific-Suffix: | AM DD |
| Bishop Of: | Bishop of the Australian Defence Force |
| See: | Military Ordinariate of Australia |
| Enthroned: | 27 February 1985 |
| Ended: | 15 July 2003 |
| Predecessor: | John Aloysius Morgan |
| Successor: | Max Leroy Davis |
| Ordination: | 21 July 1956 |
| Consecration: | 27 February 1985 |
| Other Post: | Titular Bishop of Mopta |
| Birth Date: | 27 August 1928 |
| Death Place: | Canberra, ACT |
| Religion: | Roman Catholic |
Geoffrey Mayne (27 August 1928 – 14 September 2003) was the Catholic Bishop of the Australian Defence Force from 27 February 1985 until 15 July 2003.