Residents of Newmarket, Town—Ville — Sub-district E, surnames O (1881 Census)
| # | Surname | Given | Sex | Age | Religion | Origin | Birthplace | Occupation | HH |
| 23 | obrien | mary | F | 36 | Roman Catholic | Irish | Ontario | Seamstress | 197 |
| 24 | obrien | michael | M | 60 | Roman Catholic | Irish | Ireland | Farmers, general and nfs | 119 |
| 20 | oconnor | ann | F | 62 | Presbyterian | Irish | Ireland | No Occupation Listed | 166 |
| 21 | oconnor | thomas | M | 21 | Presbyterian | Irish | Ontario | Labourers nfs | 166 |
| 6 | ogleby | clarrissa | F | 79 | Christian | English | United States | Weavers | 331 |
| 7 | ogleby | clarrissa | F | 23 | Christian | English | Ontario | No Occupation Listed | 331 |
| 22 | ohara | margaret | F | 62 | Roman Catholic | Irish | Ireland | No Occupation Listed | 6 |
| 21 | ohara | martin | M | 64 | Roman Catholic | Irish | Ireland | Weavers | 6 |
| 15 | oliver | addie | F | 12 | Presbyterian | Scottish | Ontario | No Occupation Listed | 74 |
| 17 | oliver | arthur | M | 5 | Presbyterian | Scottish | Ontario | No Occupation Listed | 74 |
| 18 | oliver | blake | M | 0 | Presbyterian | Scottish | Ontario | No Occupation Listed | 74 |
| 13 | oliver | byron | M | 16 | Presbyterian | Scottish | Ontario | No Occupation Listed | 74 |
| 16 | oliver | edmund | M | 10 | Presbyterian | Scottish | Ontario | No Occupation Listed | 74 |
| 12 | oliver | mary | F | 38 | Presbyterian | English | Ontario | No Occupation Listed | 74 |
| 11 | oliver | william | M | 45 | Presbyterian | Scottish | Ontario | Coach, carriage, cart and wagon makers | 74 |
| 14 | oliver | willie | M | 15 | Presbyterian | Scottish | Ontario | No Occupation Listed | 74 |
| 4 | oneil | annie | F | 20 | Roman Catholic | Irish | Ontario | No Occupation Listed | 112 |
| 6 | oneil | elizabeth | F | 15 | Roman Catholic | Irish | Ontario | No Occupation Listed | 112 |
| 9 | oneil | felix | M | 8 | Roman Catholic | Irish | Ontario | No Occupation Listed | 112 |
| 2 | oneil | helen | F | 40 | Roman Catholic | Irish | Ireland | No Occupation Listed | 112 |
| 3 | oneil | helen | F | 21 | Roman Catholic | Irish | Ontario | Dressmakers | 112 |
| 11 | oneil | james | M | 2 | Roman Catholic | Irish | Ontario | No Occupation Listed | 112 |
| 1 | oneil | john | M | 58 | Roman Catholic | Irish | Ireland | Labourers nfs | 112 |
| 5 | oneil | john | M | 18 | Roman Catholic | Irish | Ontario | Labourers nfs | 112 |
| 10 | oneil | maggie | F | 7 | Roman Catholic | Irish | Ontario | No Occupation Listed | 112 |
| 8 | oneil | sarah | F | 11 | Roman Catholic | Irish | Ontario | No Occupation Listed | 112 |
| 7 | oneil | thomas | M | 12 | Roman Catholic | Irish | Ontario | No Occupation Listed | 112 |
| 13 | ough | libbie | F | 22 | Episcopal Methodist | English | Ontario | Servants nfs | 332 |
| 2 | owen | arthur | M | 12 | Anglican | English | British Columbia | No Occupation Listed | 147 |
| 4 | owen | beatrice | F | 9 | Anglican | English | British Columbia | No Occupation Listed | 147 |
| 25 | owen | cathrine | F | 17 | Anglican | English | England | No Occupation Listed | 147 |
| 24 | owen | clementine | F | 38 | Anglican | English | England | No Occupation Listed | 147 |
| 5 | owen | eleanor | F | 7 | Anglican | English | Ontario | No Occupation Listed | 147 |
| 6 | owen | gwendolin | F | 4 | Anglican | English | Ontario | No Occupation Listed | 147 |
| 23 | owen | henry | M | 48 | Anglican | English | England | Ministers of Religion | 147 |
| 1 | owen | hugh | M | 14 | Anglican | English | England | No Occupation Listed | 147 |
| 3 | owen | isabel | F | 10 | Anglican | English | British Columbia | No Occupation Listed | 147 |
| 16 | owens | clara | F | 1 | Anglican | English | England | No Occupation Listed | 159 |
| 15 | owens | matilda | F | 21 | Anglican | English | England | No Occupation Listed | 159 |
| 14 | owens | michael | M | 36 | Roman Catholic | Irish | United States | Machinists | 159 |