Residents of Niagara, Township — Sub-district B, surnames O (1881 Census)
| # | Surname | Given | Sex | Age | Religion | Origin | Birthplace | Occupation | HH |
| 17 | obrien | james | M | 40 | Roman Catholic | Irish | Ireland | No Occupation Listed | 36 |
| 18 | obrien | mary | F | 44 | Roman Catholic | Irish | Ireland | No Occupation Listed | 36 |
| 19 | obrien | mary | F | 55 | Roman Catholic | Irish | Ireland | No Occupation Listed | 97 |
| 20 | obrien | thomas | M | 22 | Roman Catholic | Irish | Quebec | Labourers nfs | 97 |
| 18 | oliver | alexander | M | 5 | Roman Catholic | English | Ontario | No Occupation Listed | 144 |
| 20 | oliver | ida | F | 6 | Anglican | Scottish | Ontario | No Occupation Listed | 117 |
| 24 | oliver | jane | F | 60 | Anglican | Scottish | Ireland | No Occupation Listed | 117 |
| 18 | oliver | john | M | 38 | Anglican | Scottish | Ontario | Farmers, general and nfs | 117 |
| 19 | oliver | mackenzie | M | 3 | Roman Catholic | English | Ontario | No Occupation Listed | 144 |
| 19 | oliver | margaret | F | 38 | Anglican | Irish | Ontario | No Occupation Listed | 117 |
| 17 | oliver | margaret | F | 31 | Roman Catholic | English | Ontario | No Occupation Listed | 144 |
| 21 | oliver | mary | F | 2 | Anglican | Scottish | Ontario | No Occupation Listed | 117 |
| 20 | oliver | thomas | M | 1 | Roman Catholic | English | Ontario | No Occupation Listed | 144 |
| 21 | oneil | frank | M | 7 | Roman Catholic | Irish | Ireland | No Occupation Listed | 36 |
| 20 | oneil | james | M | 7 | Roman Catholic | Irish | Ireland | No Occupation Listed | 36 |
| 19 | oneil | johannah | F | 35 | Roman Catholic | Irish | Ireland | No Occupation Listed | 36 |
| 6 | orr | hannah | F | 77 | Presbyterian | English | Ontario | No Occupation Listed | 26 |