Residents of Fergus, VL — Sub-district B, surnames O (1881 Census)
| # | Surname | Given | Sex | Age | Religion | Origin | Birthplace | Occupation | HH |
| 8 | oconor | agness | F | 29 | Roman Catholic | Irish | Ontario | Dressmakers | 327 |
| 12 | oconor | danial | M | 2 | Roman Catholic | Irish | Ontario | No Occupation Listed | 327 |
| 11 | oconor | ellenna | F | 3 | Roman Catholic | Irish | Ontario | No Occupation Listed | 327 |
| 10 | oconor | helen | F | 26 | Roman Catholic | Irish | Ontario | No Occupation Listed | 327 |
| 9 | oconor | julia | F | 32 | Roman Catholic | Irish | Ontario | Dressmakers | 327 |
| 18 | ogelvie | archibald | M | 21 | Presbyterian | Scottish | Quebec | Teachers (unspecified) | 299 |
| 2 | orange | mary | F | 81 | Anglican | Irish | Ireland | No Occupation Listed | 224 |
| 6 | orchardson | alexander | M | 5 | Presbyterian | Scottish | Ontario | No Occupation Listed | 35 |
| 5 | orchardson | catherin | F | 29 | Presbyterian | Scottish | Scotland | No Occupation Listed | 35 |
| 7 | orchardson | james | M | 4 | Presbyterian | Scottish | Ontario | No Occupation Listed | 35 |
| 4 | orchardson | william | M | 29 | Presbyterian | Scottish | Scotland | Bakers | 35 |
| 6 | oreilly | gerald | M | 24 | Anglican | Irish | Ontario | Medical Doctors and physicians (not UK) | 76 |
| 23 | orr | bertha | F | 8 | Disciple of Christ | English | Ontario | No Occupation Listed | 259 |
| 3 | orton | ann | F | 39 | Anglican | English | Ontario | No Occupation Listed | 76 |
| 2 | orton | george | M | 44 | Anglican | English | Ontario | Medical Doctors and physicians (not UK) | 76 |
| 5 | orton | harriet | F | 13 | Anglican | English | Ontario | No Occupation Listed | 76 |
| 4 | orton | maud | F | 15 | Anglican | English | Ontario | No Occupation Listed | 76 |
| 24 | osoane | helen | F | 48 | Roman Catholic | Irish | Ireland | No Occupation Listed | 317 |