Residents of Grantham — Sub-district B, surnames O (1881 Census)
| # | Surname | Given | Sex | Age | Religion | Origin | Birthplace | Occupation | HH |
| 17 | obrien | alice | F | 53 | Roman Catholic | Irish | Ireland | No Occupation Listed | 102 |
| 7 | obrien | ellen | F | 59 | Roman Catholic | Irish | Ireland | No Occupation Listed | 64 |
| 8 | obrien | john | M | 23 | Roman Catholic | Irish | Ontario | Labourers nfs | 64 |
| 10 | obrien | kate | F | 21 | Roman Catholic | Irish | Ontario | No Occupation Listed | 64 |
| 6 | obrien | patrick | M | 60 | Roman Catholic | Irish | Ireland | Labourers nfs | 64 |
| 16 | obrien | patrick | M | 66 | Roman Catholic | Irish | Ireland | Teachers (unspecified) | 102 |
| 9 | obrien | timothy | M | 19 | Roman Catholic | Irish | Ontario | Labourers nfs | 64 |
| 6 | oconnor | andrew | M | 60 | Roman Catholic | Irish | Ireland | Farmers, general and nfs | 38 |
| 9 | oconnor | daniel | M | 21 | Roman Catholic | Irish | Ontario | Farmers, general and nfs | 38 |
| 8 | oconnor | james | M | 22 | Roman Catholic | Irish | Ontario | Farmers, general and nfs | 38 |
| 7 | oconnor | mary | F | 50 | Roman Catholic | Irish | Ireland | No Occupation Listed | 38 |
| 10 | oconnor | stephen | M | 16 | Roman Catholic | Irish | Ontario | Clerk, nfs | 38 |
| 11 | oconnor | thomas | M | 14 | Roman Catholic | Irish | Ontario | No Occupation Listed | 38 |
| 12 | oconnor | thresa | F | 11 | Roman Catholic | Irish | Ontario | No Occupation Listed | 38 |
| 3 | oill | jabez | M | 57 | Anglican | German | Ontario | Farmers, general and nfs | 103 |
| 5 | oill | john | M | 25 | Anglican | German | Ontario | Farmers, general and nfs | 103 |
| 4 | oill | susan | F | 45 | Anglican | French | Ontario | No Occupation Listed | 103 |
| 19 | omara | catharine | F | 10 | Roman Catholic | Irish | Ontario | No Occupation Listed | 142 |
| 15 | omara | james | M | 20 | Roman Catholic | Irish | Ontario | No Occupation Listed | 142 |
| 16 | omara | john | M | 18 | Roman Catholic | Irish | Ontario | No Occupation Listed | 142 |
| 13 | omara | margaret | F | 48 | Roman Catholic | Irish | Ireland | No Occupation Listed | 142 |
| 18 | omara | margaret | F | 12 | Roman Catholic | Irish | Ontario | No Occupation Listed | 142 |
| 14 | omara | michael | M | 22 | Roman Catholic | Irish | Ontario | Farmers, general and nfs | 142 |
| 12 | omara | patrick | M | 60 | Roman Catholic | Irish | Ireland | Farmers, general and nfs | 142 |
| 17 | omara | patrick | M | 16 | Roman Catholic | Irish | Ontario | No Occupation Listed | 142 |
| 21 | omara | patrick | M | 50 | Roman Catholic | Irish | Ireland | Farmers, general and nfs | 187 |
| 20 | omara | thomas | M | 6 | Roman Catholic | Irish | Ontario | No Occupation Listed | 142 |
| 21 | omara | william | M | 3 | Roman Catholic | Irish | Ontario | No Occupation Listed | 142 |
| 22 | omara | winnifred | F | 52 | Roman Catholic | Irish | Ireland | No Occupation Listed | 187 |
| 23 | omara | winnifred | F | 15 | Roman Catholic | Irish | Ontario | No Occupation Listed | 187 |
| 22 | oneill | ellen | F | 6 | Anglican | English | England | No Occupation Listed | 38 |
| 20 | oneill | emma | F | 14 | Anglican | English | England | No Occupation Listed | 38 |
| 21 | oneill | henry | M | 17 | Anglican | English | England | No Occupation Listed | 38 |
| 19 | oneill | margarat | F | 18 | Anglican | English | England | No Occupation Listed | 38 |
| 18 | oneill | sarah | F | 45 | Anglican | English | England | No Occupation Listed | 38 |
| 17 | oneill | thomas | M | 47 | Anglican | English | England | Farmers, general and nfs | 38 |