Residents of St. Mary's, Town—Ville — Sub-district B, surnames O (1881 Census)
| # | Surname | Given | Sex | Age | Religion | Origin | Birthplace | Occupation | HH |
| 22 | obrian | ann | F | 54 | Roman Catholic | Irish | Ireland | No Occupation Listed | 373 |
| 2 | obrian | annie | F | 23 | Roman Catholic | Irish | Ontario | Servants nfs | 373 |
| 3 | obrian | elizabeth | F | 20 | Roman Catholic | Irish | Ontario | Servants nfs | 373 |
| 4 | obrian | ellen | F | 17 | Roman Catholic | Irish | Ontario | No Occupation Listed | 373 |
| 5 | obrian | john | M | 15 | Roman Catholic | Irish | Ontario | No Occupation Listed | 373 |
| 23 | obrian | margaret | F | 36 | Roman Catholic | Irish | Ireland | No Occupation Listed | 373 |
| 1 | obrian | mary | F | 25 | Roman Catholic | Irish | Ontario | Servants nfs | 373 |
| 24 | obrian | matthew | M | 34 | Roman Catholic | Irish | Ireland | Machinists | 373 |
| 25 | obrian | patrick | M | 32 | Roman Catholic | Irish | Ireland | Labourers nfs | 373 |
| 16 | oconner | annie | F | 2 | Roman Catholic | Irish | Ontario | No Occupation Listed | 65 |
| 10 | oconner | bridget | F | 18 | Roman Catholic | Irish | Ontario | No Occupation Listed | 107 |
| 14 | oconner | catherine | F | 29 | Roman Catholic | Irish | Ireland | No Occupation Listed | 65 |
| 13 | oconner | john | M | 35 | Roman Catholic | Irish | Ireland | Farmers, general and nfs | 65 |
| 9 | oconner | mary | F | 58 | Roman Catholic | Irish | Ireland | No Occupation Listed | 107 |
| 15 | oconner | mary | F | 5 | Roman Catholic | Irish | Ontario | No Occupation Listed | 65 |
| 8 | oconner | michael | M | 54 | Roman Catholic | Irish | Ireland | Labourers nfs | 107 |
| 11 | oconner | michael | M | 15 | Roman Catholic | Irish | Ontario | No Occupation Listed | 107 |
| 6 | oconnor | john | M | 60 | Roman Catholic | Irish | Ireland | Labourers nfs | 374 |
| 9 | oconnor | julia | F | 21 | Roman Catholic | Irish | Ontario | Tailors and tailoresses | 374 |
| 7 | oconnor | maggie | F | 25 | Roman Catholic | Irish | Ireland | No Occupation Listed | 374 |
| 8 | oconnor | mary | F | 23 | Roman Catholic | Irish | Ontario | Tailors and tailoresses | 374 |
| 18 | oddy | bartholemue | M | 10 | Anglican | English | Ontario | No Occupation Listed | 320 |
| 20 | oddy | elizabeth | F | 56 | Anglican | English | England | No Occupation Listed | 39 |
| 16 | oddy | elizabeth | F | 7 | Anglican | English | Ontario | No Occupation Listed | 158 |
| 24 | oddy | fanny | F | 13 | Anglican | English | Ontario | No Occupation Listed | 39 |
| 23 | oddy | harriet | F | 17 | Anglican | English | Ontario | No Occupation Listed | 39 |
| 17 | oddy | harriet | F | 1 | Anglican | English | Ontario | No Occupation Listed | 158 |
| 19 | oddy | jacob | M | 55 | Anglican | English | England | Hotel Keepers and Managers | 39 |
| 9 | oddy | john | M | 52 | Anglican | English | England | Labourers nfs | 158 |
| 14 | oddy | john | M | 11 | Anglican | English | Ontario | No Occupation Listed | 158 |
| 21 | oddy | joseph | M | 27 | Anglican | English | England | Clerk, nfs | 39 |
| 15 | oddy | joseph | M | 9 | Anglican | English | Ontario | No Occupation Listed | 158 |
| 10 | oddy | mary | F | 41 | Anglican | Scottish | Scotland | No Occupation Listed | 158 |
| 11 | oddy | mary | F | 17 | Anglican | English | Ontario | No Occupation Listed | 158 |
| 17 | oddy | mary | F | 12 | Anglican | English | Ontario | No Occupation Listed | 320 |
| 13 | oddy | thos | M | 13 | Anglican | English | Ontario | No Occupation Listed | 158 |
| 22 | oddy | william | M | 23 | Anglican | English | Ontario | Tailors and tailoresses | 39 |
| 12 | oddy | wm | M | 15 | Anglican | English | Ontario | Labourers nfs | 158 |
| 11 | odea | annie | F | 6 | Roman Catholic | Irish | Ontario | No Occupation Listed | 319 |
| 6 | odea | bridget | F | 43 | Roman Catholic | Irish | Ireland | No Occupation Listed | 319 |
| 7 | odea | margaret | F | 15 | Roman Catholic | Irish | Ontario | No Occupation Listed | 319 |
| 10 | odea | mary | F | 8 | Roman Catholic | Irish | Ontario | No Occupation Listed | 319 |
| 5 | odea | michael | M | 45 | Roman Catholic | Irish | Ireland | Quarrymen | 319 |
| 9 | odea | michael | M | 10 | Roman Catholic | Irish | Ontario | No Occupation Listed | 319 |
| 8 | odea | thos | M | 12 | Roman Catholic | Irish | Ontario | No Occupation Listed | 319 |
| 12 | odea | wm | M | 2 | Roman Catholic | Irish | Ontario | No Occupation Listed | 319 |
| 17 | odett | catharine | F | 33 | Methodist | Irish | Ontario | No Occupation Listed | 189 |
| 16 | odett | henry | M | 34 | Methodist | French | Quebec | Carpenters | 189 |
| 19 | odett | lewis | M | 5 | Methodist | French | Ontario | No Occupation Listed | 189 |
| 21 | odett | mabel | F | 0 | Methodist | French | Ontario | No Occupation Listed | 189 |
| 18 | odett | mattie | F | 7 | Methodist | French | United States | No Occupation Listed | 189 |
| 20 | odett | thos | M | 3 | Methodist | French | Ontario | No Occupation Listed | 189 |
| 12 | oharra | elizabeth | F | 35 | Presbyterian | Irish | Ontario | No Occupation Listed | 250 |
| 14 | oharra | elizabeth | F | 4 | Presbyterian | Irish | Ontario | No Occupation Listed | 250 |
| 13 | oharra | george | M | 5 | Presbyterian | Irish | Ontario | No Occupation Listed | 250 |
| 16 | oharra | john | M | 0 | Presbyterian | Irish | Ontario | No Occupation Listed | 250 |
| 15 | oharra | katherine | F | 2 | Presbyterian | Irish | Ontario | No Occupation Listed | 250 |
| 11 | oharra | william | M | 46 | Presbyterian | Irish | Ireland | Manufacturers | 250 |
| 8 | oldfield | anthony | M | 46 | Anglican | English | England | Labourers nfs | 380 |
| 9 | oldfield | mary | F | 45 | Anglican | English | England | No Occupation Listed | 380 |
| 6 | olimer | mary | F | 72 | Anglican | English | England | No Occupation Listed | 312 |
| 5 | olimer | samuel | M | 68 | Anglican | English | England | No Occupation Listed | 312 |
| 23 | oliver | eliza | F | 48 | Presbyterian | Irish | Quebec | No Occupation Listed | 68 |
| 25 | oliver | ida | F | 16 | Presbyterian | Scottish | Ontario | No Occupation Listed | 68 |
| 22 | oliver | james | M | 53 | Presbyterian | Scottish | Scotland | Bakers | 68 |
| 24 | oliver | jennie | F | 22 | Presbyterian | Scottish | Ontario | No Occupation Listed | 68 |
| 2 | oliver | jessie | F | 13 | Presbyterian | Scottish | Ontario | No Occupation Listed | 68 |
| 3 | oliver | maggie | F | 11 | Presbyterian | Scottish | Ontario | No Occupation Listed | 68 |
| 1 | oliver | william | M | 29 | Presbyterian | Scottish | Ontario | Tinsmiths and Tinners and Tinkers | 68 |
| 22 | omara | ann | F | 52 | Roman Catholic | Irish | Ontario | Servants nfs | 142 |
| 1 | othen | charles | M | 8 | Episcopal | English | Ontario | No Occupation Listed | 257 |
| 25 | othen | eliza | F | 10 | Episcopal | English | Ontario | No Occupation Listed | 257 |
| 2 | othen | george | M | 5 | Episcopal | English | Ontario | No Occupation Listed | 257 |
| 22 | othen | james | M | 42 | Episcopal | English | England | Engineers (US) nfs | 257 |
| 24 | othen | lizzie | F | 13 | Episcopal | English | England | No Occupation Listed | 257 |
| 23 | othen | martha | F | 35 | Episcopal | English | England | No Occupation Listed | 257 |
| 3 | othen | martha | F | 2 | Episcopal | English | Ontario | No Occupation Listed | 257 |
| 23 | owens | ellen | F | 26 | Roman Catholic | Irish | Ontario | No Occupation Listed | 193 |
| 24 | owens | margaret | F | 4 | Roman Catholic | Irish | Ontario | No Occupation Listed | 193 |
| 25 | owens | maud | F | 1 | Roman Catholic | Irish | Ontario | No Occupation Listed | 193 |