Residents of Dundas, Town—Ville — Sub-district A, surnames O (1881 Census)
| # | Surname | Given | Sex | Age | Religion | Origin | Birthplace | Occupation | HH |
| 6 | obrian | joseph | M | 8 | Roman Catholic | Irish | Ontario | No Occupation Listed | 332 |
| 7 | obrian | michal | M | 6 | Roman Catholic | Irish | Ontario | No Occupation Listed | 332 |
| 24 | oconnor | bridget | F | 66 | Roman Catholic | Irish | Ireland | No Occupation Listed | 184 |
| 7 | oconnor | cathrine | F | 7 | Roman Catholic | Irish | Ontario | No Occupation Listed | 144 |
| 1 | oconnor | cornelious | M | 26 | Roman Catholic | Irish | Ontario | Machinists | 184 |
| 10 | oconnor | cristeena | F | 1 | Roman Catholic | Irish | Ontario | No Occupation Listed | 144 |
| 25 | oconnor | daniel | M | 35 | Roman Catholic | Irish | Ireland | Dealer, merchant etc. (Wholesale & retail trade) | 184 |
| 2 | oconnor | edmon | M | 23 | Roman Catholic | Irish | Ontario | Metal moulders and coremakers and workers in… | 184 |
| 9 | oconnor | ellin | F | 3 | Roman Catholic | Irish | Ontario | No Occupation Listed | 144 |
| 3 | oconnor | jeremia | M | 35 | Roman Catholic | Irish | Ireland | Carpenters | 144 |
| 5 | oconnor | john | M | 11 | Roman Catholic | Irish | Ontario | No Occupation Listed | 144 |
| 8 | oconnor | marey | F | 5 | Roman Catholic | Irish | Ontario | No Occupation Listed | 144 |
| 4 | oconnor | mary | F | 35 | Roman Catholic | Irish | Ireland | No Occupation Listed | 144 |
| 6 | oconnor | patrick | M | 9 | Roman Catholic | Irish | Ontario | No Occupation Listed | 144 |
| 1 | odanahse | james | M | 0 | Roman Catholic | Irish | Ontario | No Occupation Listed | 332 |
| 20 | odea | james | M | 10 | Roman Catholic | Irish | Ontario | No Occupation Listed | 332 |
| 19 | odea | michal | M | 11 | Roman Catholic | Irish | Ontario | No Occupation Listed | 332 |
| 21 | odea | thimothey | M | 9 | Roman Catholic | Irish | Ontario | No Occupation Listed | 332 |
| 7 | odonel | joanna | F | 44 | Roman Catholic | Irish | Ireland | No Occupation Listed | 204 |
| 6 | odonel | patrick | M | 52 | Roman Catholic | Irish | Ireland | Labourers nfs | 204 |
| 20 | odonell | james | M | 14 | Roman Catholic | Irish | Ontario | No Occupation Listed | 270 |
| 19 | odonnell | mary | F | 21 | Roman Catholic | Irish | Ontario | No Occupation Listed | 270 |
| 5 | ogg | catharine | F | 27 | Presbyterian | Irish | Ontario | No Occupation Listed | 265 |
| 4 | ogg | charls | M | 28 | Presbyterian | Scottish | Ontario | Engineers (US) nfs | 265 |
| 6 | ogg | sharlot | F | 0 | Presbyterian | Irish | Ontario | No Occupation Listed | 265 |
| 15 | ogrady | bridget | F | 60 | Roman Catholic | Irish | Ireland | No Occupation Listed | 199 |
| 16 | ogrady | john | M | 26 | Roman Catholic | Irish | Ontario | Labourers nfs | 199 |
| 14 | ogrady | william | M | 73 | Roman Catholic | Irish | Ireland | Labourers nfs | 199 |
| 19 | oleary | ann | F | 54 | Roman Catholic | French | Ireland | No Occupation Listed | 193 |
| 18 | oleary | elen | F | 64 | Roman Catholic | French | Ireland | No Occupation Listed | 193 |
| 7 | oneil | anora | F | 7 | Roman Catholic | Irish | Ireland | No Occupation Listed | 153 |
| 4 | oneil | ceselia | F | 30 | Roman Catholic | Irish | Ireland | No Occupation Listed | 153 |
| 6 | oneil | ceselia | F | 11 | Roman Catholic | Irish | Ireland | No Occupation Listed | 153 |
| 8 | oneil | katie | F | 5 | Roman Catholic | Irish | Ontario | No Occupation Listed | 153 |
| 8 | oneil | michael | M | 60 | Roman Catholic | Irish | Ireland | No Occupation Listed | 332 |
| 5 | oneil | michel | M | 70 | Roman Catholic | Irish | Ireland | Mason nfs or combined | 241 |
| 5 | oneil | minne | F | 14 | Roman Catholic | Irish | Ireland | No Occupation Listed | 153 |
| 3 | oneil | thomas | M | 33 | Roman Catholic | Irish | Ireland | Bakers | 153 |
| 9 | oneil | thomas | M | 3 | Roman Catholic | Irish | Ontario | No Occupation Listed | 153 |
| 9 | oreman | james | M | 12 | Presbyterian | Scottish | Scotland | Factory labourers (non-specified manufacturing) | 25 |
| 7 | oreman | jenet | F | 38 | Presbyterian | Scottish | Scotland | No Occupation Listed | 25 |
| 11 | oreman | jennet | F | 4 | Presbyterian | Scottish | Scotland | No Occupation Listed | 25 |
| 8 | oreman | margret | F | 13 | Presbyterian | Scottish | Scotland | Factory labourers (non-specified manufacturing) | 25 |
| 10 | oreman | william | M | 9 | Presbyterian | Scottish | Scotland | No Occupation Listed | 25 |
| 15 | oriley | john | M | 60 | Roman Catholic | Irish | Ireland | Ministers of Religion | 81 |
| 2 | oriley | john | M | 9 | Roman Catholic | Irish | Ontario | No Occupation Listed | 332 |
| 23 | oristha | frances | M | 55 | Roman Catholic | French | France | Weavers | 120 |
| 25 | oselar | marion | F | 35 | Presbyterian | Scottish | Ontario | No Occupation Listed | 118 |
| 12 | oselor | ethel | F | 10 | Anglican | English | Ontario | No Occupation Listed | 114 |
| 9 | osler | alexander | M | 10 | Anglican | English | Ontario | No Occupation Listed | 114 |
| 8 | osler | ellen | F | 34 | Anglican | English | England | No Occupation Listed | 114 |
| 7 | osler | emelen | F | 74 | Anglican | English | England | No Occupation Listed | 114 |
| 6 | osler | feathestone | M | 75 | Anglican | English | England | Ministers of Religion | 114 |
| 5 | out | austan | M | 1 | Anglican | English | Ontario | No Occupation Listed | 81 |
| 1 | out | hariett | F | 24 | Anglican | English | England | Factory labourers (non-specified manufacturing) | 81 |
| 2 | out | mary | F | 14 | Anglican | English | England | No Occupation Listed | 81 |
| 3 | out | sarah | F | 10 | Anglican | English | England | No Occupation Listed | 81 |
| 25 | out | thomas | M | 36 | Anglican | English | England | Labourers nfs | 81 |
| 4 | out | thomas | M | 7 | Anglican | English | England | No Occupation Listed | 81 |