Residents of Ernestown — Sub-district D, surnames O (1881 Census)
| # | Surname | Given | Sex | Age | Religion | Origin | Birthplace | Occupation | HH |
| 2 | oak | fred | M | 0 | Methodist | English | Ontario | No Occupation Listed | 223 |
| 1 | oak | maud | F | 4 | Methodist | English | Ontario | No Occupation Listed | 223 |
| 22 | obrien | patrick | M | 62 | Roman Catholic | Irish | Ireland | Servants nfs | 32 |
| 22 | oke | alma | F | 13 | Methodist | English | Ontario | No Occupation Listed | 223 |
| 21 | oke | annie | F | 15 | Methodist | English | Ontario | No Occupation Listed | 223 |
| 24 | oke | getta | F | 8 | Methodist | English | Ontario | No Occupation Listed | 223 |
| 25 | oke | ida | F | 6 | Methodist | English | Ontario | No Occupation Listed | 223 |
| 23 | oke | magdeline | F | 11 | Methodist | English | Ontario | No Occupation Listed | 223 |
| 20 | oke | susannah | F | 36 | Methodist | English | Ontario | No Occupation Listed | 223 |
| 19 | oke | thomas | M | 40 | Methodist | English | England | Farmers, general and nfs | 223 |
| 22 | omarah | james | M | 11 | Roman Catholic | Irish | Ontario | No Occupation Listed | 128 |
| 21 | omarah | matilda | F | 5 | Roman Catholic | Irish | Ontario | No Occupation Listed | 128 |
| 20 | omarah | miriah | F | 9 | Roman Catholic | Irish | Ontario | No Occupation Listed | 128 |
| 19 | omarah | william | M | 45 | Roman Catholic | Irish | Ireland | Farmers, general and nfs | 128 |
| 18 | omarrah | john | M | 29 | Roman Catholic | Irish | Ontario | Farmers, general and nfs | 138 |
| 19 | omarrah | nellie | F | 20 | Roman Catholic | French | Ontario | No Occupation Listed | 138 |
| 18 | oneil | alicia | F | 45 | Roman Catholic | Irish | Ireland | No Occupation Listed | 285 |
| 21 | oneil | elizabeth | F | 54 | Methodist | German | Ontario | No Occupation Listed | 245 |
| 17 | oneil | james | M | 72 | Roman Catholic | Irish | Ireland | Farmers, general and nfs | 285 |
| 20 | oneil | john | M | 57 | Methodist | Irish | Ontario | Farmers, general and nfs | 245 |
| 24 | oneil | john | M | 16 | Methodist | Irish | Ontario | Farmers, general and nfs | 245 |
| 25 | oneil | nelson | M | 13 | Methodist | Irish | Ontario | Farmers, general and nfs | 245 |
| 22 | oneil | norman | M | 23 | Methodist | Irish | Ontario | Farmers, general and nfs | 245 |
| 23 | oneil | reuben | M | 19 | Methodist | Irish | Ontario | Farmers, general and nfs | 245 |
| 24 | opperman | john | M | 16 | Anglican | English | England | Labourers nfs | 79 |
| 14 | osborn | david | M | 52 | Methodist | German | Ontario | Labourers nfs | 211 |
| 22 | osborn | henry | M | 28 | Methodist | German | Ontario | Farmers, general and nfs | 206 |
| 18 | osborn | james | M | 15 | Methodist | German | Ontario | Labourers nfs | 211 |
| 16 | osborn | julia | F | 25 | Methodist | German | Ontario | No Occupation Listed | 211 |
| 17 | osborn | maggie | F | 18 | Methodist | German | Ontario | No Occupation Listed | 211 |
| 15 | osborn | margaret | F | 52 | Methodist | English | Ontario | No Occupation Listed | 211 |
| 23 | osborn | sarah | F | 23 | Methodist | English | Ontario | No Occupation Listed | 206 |
| 19 | ovens | cathrine | F | 19 | Presbyterian | Scottish | Ontario | No Occupation Listed | 61 |
| 16 | ovens | eliza | F | 57 | Presbyterian | German | Ontario | No Occupation Listed | 61 |
| 17 | ovens | john | M | 27 | Presbyterian | Scottish | Ontario | Farmers, general and nfs | 61 |
| 18 | ovens | rufus | M | 22 | Presbyterian | Scottish | Ontario | No Occupation Listed | 61 |
| 15 | ovens | william | M | 67 | Presbyterian | Scottish | Scotland | Farmers, general and nfs | 61 |