| William Rabb Beatty | |
| Office1: | Ontario MPP |
| Term Start1: | 1894 |
| Term End1: | 1902 |
| Predecessor1: | James Sharpe |
| Successor1: | Joseph Milton Carr |
| Constituency1: | Parry Sound |
| Party: | Patrons of Industry (Liberal) |
| Birth Date: | 11 June 1851 |
| Death Place: | Parry Sound, Ontario |
| Occupation: | Businessman |
William Rabb Beatty (June 11, 1851 - February 8, 1905) was an Ontario businessman and political figure. He represented Parry Sound in the Legislative Assembly of Ontario as a Liberal-Patrons of Industry member from 1894 to 1898 and as a Liberal from 1898 to 1902.
He was the manager for the Beatty Line, a steamship company operating on the Great Lakes. His brother Walter Beatty also served in the provincial assembly. Beatty lived in Parry Sound.