| A. A. Mahaffy | |
| Office1: | Ontario MPP |
| Term Start1: | 1903 |
| Term End1: | 1912 |
| Predecessor1: | Samuel Bridgeland |
| Successor1: | Samuel Armstrong |
| Constituency1: | Muskoka |
| Party: | Conservative |
| Birth Date: | 30 December 1861 |
| Birth Place: | Grey County, Canada West |
| Death Place: | Bracebridge, Ontario |
| Occupation: | Lawyer |
Arthur Arnold Mahaffy (December 30, 1861 – November 3, 1947) was an Ontario barrister and political figure. He represented Muskoka in the Legislative Assembly of Ontario from 1903 to 1912 as a Conservative member.
He was born in Grey County, Canada West, the son of doctor John Mahaffy. In 1891, he married Alice Rosalie Thomson.[1] He was elected to the provincial assembly in a 1903 by-election held after the death of Samuel Bridgeland.
Mahaffy later served as a judge. He died in Bracebridge on November 3, 1947.[2]