| William Mortimer | |
| Birth Name: | William Mortimer |
| Birth Date: | 1874 4, df=y |
| Birth Place: | Warrington, England |
| Death Place: | Crowborough, England |
| Position: | Forward |
| Amatteam1: | Cambridge University R.U.F.C. |
| Amatteam2: | Marlborough Nomads |
| Repteam1: | British Isles |
| Repteam2: | England |
| Repyears1: | 1896 |
| Repyears2: | 1899 |
| Repcaps1: | 4 |
| Repcaps2: | 1 |
| Reppoints1: | 0 |
| Reppoints2: | 0 |
| School: | Marlborough College |
| University: | Trinity College, Cambridge |
William Mortimer (2 April 1874 – 31 October 1916)[1] was an English rugby union forward who played club rugby for Marlborough Nomads and was capped for England, and was part of the British Isles tour to South Africa in 1896.
Mortimer was born in Warrington, Cheshire in 1874 to William Mortimer of Frodsham. He was educated at Marlborough College before matriculating to Trinity College, Cambridge in 1893. He worked on the London Stock Exchange.