Residents of Niagara, Township — Sub-district A, surnames O (1881 Census)
| # | Surname | Given | Sex | Age | Religion | Origin | Birthplace | Occupation | HH |
| 22 | _oltts | anne | F | 15 | Anglican | Welsh | Wales | Servants nfs | 91 |
| 11 | oconnor | annie | F | 27 | Roman Catholic | Irish | Ireland | No Occupation Listed | 102 |
| 13 | oconnor | annie | F | 6 | Roman Catholic | Irish | United States | No Occupation Listed | 102 |
| 10 | oconnor | domonic | M | 39 | Roman Catholic | Irish | Ireland | Quarrymen | 102 |
| 14 | oconnor | james | M | 4 | Roman Catholic | Irish | Ontario | No Occupation Listed | 102 |
| 12 | oconnor | mary | F | 7 | Roman Catholic | Irish | United States | No Occupation Listed | 102 |
| 15 | oconnor | thomas | M | 1 | Roman Catholic | Irish | Ontario | No Occupation Listed | 102 |
| 19 | odonnell | ann | F | 39 | Roman Catholic | Irish | Ireland | No Occupation Listed | 113 |
| 25 | odonnell | annie | F | 3 | Roman Catholic | Irish | Ontario | No Occupation Listed | 113 |
| 11 | odonnell | catharine | F | 27 | Roman Catholic | Irish | Ontario | No Occupation Listed | 58 |
| 23 | odonnell | daniel | M | 6 | Roman Catholic | Irish | Ontario | No Occupation Listed | 113 |
| 20 | odonnell | james | M | 11 | Roman Catholic | Irish | Ontario | No Occupation Listed | 113 |
| 24 | odonnell | mary | F | 5 | Roman Catholic | Irish | Ontario | No Occupation Listed | 113 |
| 10 | odonnell | patrick | M | 25 | Roman Catholic | Irish | Ontario | Farmers, general and nfs | 58 |
| 9 | odonnell | sarah | F | 55 | Roman Catholic | Irish | Ireland | Farmers, general and nfs | 58 |
| 1 | odonnell | sarah | F | 2 | Roman Catholic | Irish | Ontario | No Occupation Listed | 113 |
| 22 | odonnell | thomas | M | 8 | Roman Catholic | Irish | Ontario | No Occupation Listed | 113 |
| 18 | odonnell | william | M | 41 | Roman Catholic | Irish | United States | Farmers, general and nfs | 113 |
| 21 | odonnell | william | M | 9 | Roman Catholic | Irish | Ontario | No Occupation Listed | 113 |
| 7 | orchard | geo | M | 53 | Anglican | Dutch | United States | Labourers nfs | 136 |
| 23 | orr | edeth | F | 16 | Anglican | English | Ontario | No Occupation Listed | 72 |
| 25 | osmond | alice | F | 16 | Anglican | English | United States | No Occupation Listed | 88 |
| 22 | osmond | james | M | 50 | Anglican | English | England | Farmers, general and nfs | 88 |
| 24 | osmond | jenny | F | 20 | Anglican | English | United States | No Occupation Listed | 88 |
| 1 | osmond | mary | F | 13 | Anglican | English | United States | No Occupation Listed | 88 |
| 23 | osmond | rosa | F | 42 | Anglican | German | Germany | No Occupation Listed | 88 |
| 2 | osmond | rosa | F | 11 | Anglican | English | United States | No Occupation Listed | 88 |