Residents of Dunwich — Sub-district B, surnames O (1881 Census)
| # | Surname | Given | Sex | Age | Religion | Origin | Birthplace | Occupation | HH |
| 22 | obrien | angus | M | 18 | Wesleyan Methodist | Scottish | Ontario | Labourers nfs | 10 |
| 21 | obrien | james | M | 20 | Wesleyan Methodist | Scottish | Ontario | Labourers nfs | 10 |
| 19 | obrien | john | M | 52 | Wesleyan Methodist | Irish | Nova Scotia | Carpenters | 10 |
| 20 | obrien | mary | F | 53 | Wesleyan Methodist | Scottish | Ontario | No Occupation Listed | 10 |
| 23 | obrien | matilda | F | 14 | Wesleyan Methodist | Scottish | Ontario | No Occupation Listed | 10 |
| 20 | ohara | austin | M | 12 | Roman Catholic | Irish | Ontario | No Occupation Listed | 55 |
| 18 | ohara | catherine | F | 19 | Roman Catholic | Irish | Ontario | No Occupation Listed | 55 |
| 15 | ohara | james | M | 23 | Roman Catholic | Irish | Ontario | No Occupation Listed | 55 |
| 13 | ohara | john | M | 60 | Roman Catholic | Irish | Ireland | Farmers, general and nfs | 55 |
| 17 | ohara | john | M | 18 | Roman Catholic | Irish | Ontario | No Occupation Listed | 55 |
| 14 | ohara | mary | F | 50 | Roman Catholic | Irish | Ireland | No Occupation Listed | 55 |
| 16 | ohara | mary | F | 20 | Roman Catholic | Irish | Ontario | No Occupation Listed | 55 |
| 19 | ohara | thomas | M | 15 | Roman Catholic | Irish | Ontario | No Occupation Listed | 55 |
| 2 | omalley | george | M | 28 | Methodist | Scottish | Ontario | Farmers, general and nfs | 232 |
| 3 | omalley | maryana | F | 26 | Methodist | Scottish | Ontario | No Occupation Listed | 232 |
| 22 | omalley | wm | M | 20 | Roman Catholic | Irish | Ontario | Labourers nfs | 141 |
| 25 | orr | james | M | 21 | Wesleyan Methodist | Irish | United States | Teachers (unspecified) | 247 |
| 17 | osborn | alexander | M | 5 | | Irish | Ontario | No Occupation Listed | 52 |
| 15 | osborn | james | M | 11 | | Irish | Ontario | No Occupation Listed | 52 |
| 13 | osborn | jane | F | 36 | Methodist | English | Ontario | No Occupation Listed | 52 |
| 12 | osborn | john | M | 45 | Reformed Presbyterian | Irish | Ireland | Farmers, general and nfs | 52 |
| 14 | osborn | margaret | F | 14 | | Irish | Ontario | No Occupation Listed | 52 |
| 16 | osborn | mary | F | 8 | | Irish | Ontario | No Occupation Listed | 52 |
| 8 | osborne | john | M | 20 | Anglican | English | Ontario | Labourers nfs | 56 |
| 10 | ostrander | thos | M | 27 | Methodist | German | Ontario | river drivers | 18 |