Residents of Gwillimbury W-O — Sub-district B, surnames O (1881 Census)
| # | Surname | Given | Sex | Age | Religion | Origin | Birthplace | Occupation | HH |
| 17 | obrien | cathrine | F | 18 | Roman Catholic | Irish | England | No Occupation Listed | 340 |
| 13 | obrien | joannah | F | 53 | Roman Catholic | Irish | Ireland | No Occupation Listed | 340 |
| 15 | obrien | john | M | 20 | Roman Catholic | Irish | England | river drivers | 340 |
| 16 | obrien | mary | F | 18 | Roman Catholic | Irish | England | Servants nfs | 340 |
| 14 | obrien | michael | M | 22 | Roman Catholic | Irish | England | river drivers | 340 |
| 12 | obrien | patrick | M | 60 | Roman Catholic | Irish | Ireland | Farmers, general and nfs | 340 |
| 19 | obrien | timothy | M | 12 | Roman Catholic | Irish | England | No Occupation Listed | 340 |
| 18 | obrien | william | M | 15 | Roman Catholic | Irish | England | No Occupation Listed | 340 |
| 3 | oconnell | cathrine | F | 15 | Roman Catholic | Irish | Ontario | No Occupation Listed | 43 |
| 1 | oconnell | jane | F | 32 | Roman Catholic | Irish | Ontario | No Occupation Listed | 43 |
| 25 | oconnell | john | M | 44 | Roman Catholic | Irish | Ontario | Farmers, general and nfs | 43 |
| 20 | oconnell | john | M | 76 | Roman Catholic | Irish | Ireland | river drivers | 170 |
| 17 | odonnell | agnes | F | 9 | Roman Catholic | Irish | Ontario | No Occupation Listed | 29 |
| 19 | odonnell | alice | F | 54 | Presbyterian | Irish | Scotland | No Occupation Listed | 8 |
| 23 | odonnell | alice | F | 15 | Roman Catholic | Irish | Ontario | No Occupation Listed | 8 |
| 2 | odonnell | alice | F | 33 | Roman Catholic | Irish | Ontario | No Occupation Listed | 64 |
| 5 | odonnell | alonzo | M | 5 | Roman Catholic | Irish | Ontario | No Occupation Listed | 64 |
| 21 | odonnell | anthony | M | 32 | Roman Catholic | Irish | Ontario | river drivers | 63 |
| 4 | odonnell | cathrine | F | 8 | Roman Catholic | Irish | Ontario | No Occupation Listed | 64 |
| 20 | odonnell | charles | M | 34 | Roman Catholic | Irish | Ontario | river drivers | 63 |
| 16 | odonnell | elizabeth | F | 12 | Roman Catholic | Irish | Ontario | No Occupation Listed | 29 |
| 9 | odonnell | elizabeth | F | 42 | Presbyterian | Scottish | Ontario | Labourers nfs | 182 |
| 7 | odonnell | francis | M | 0 | Roman Catholic | Irish | Ontario | No Occupation Listed | 64 |
| 11 | odonnell | henry | M | 22 | Roman Catholic | Irish | Ontario | river drivers | 29 |
| 22 | odonnell | james | M | 21 | Roman Catholic | Irish | Ontario | Farmers, general and nfs | 8 |
| 24 | odonnell | james | M | 25 | Roman Catholic | Irish | Ontario | No Occupation Listed | 63 |
| 18 | odonnell | john | M | 59 | Roman Catholic | Irish | Ontario | Farmers, general and nfs | 8 |
| 20 | odonnell | john | M | 25 | Roman Catholic | Irish | Ontario | Farmers, general and nfs | 8 |
| 9 | odonnell | john | M | 48 | Roman Catholic | Irish | Ireland | Labourers nfs | 29 |
| 12 | odonnell | john | M | 20 | Roman Catholic | Irish | Ontario | river drivers | 29 |
| 22 | odonnell | john | M | 27 | Roman Catholic | Irish | Ontario | river drivers | 63 |
| 3 | odonnell | margaret | F | 11 | Roman Catholic | Irish | Ontario | No Occupation Listed | 64 |
| 21 | odonnell | mary | F | 30 | Roman Catholic | Irish | Ontario | No Occupation Listed | 8 |
| 10 | odonnell | mary | F | 50 | Roman Catholic | Irish | Ireland | No Occupation Listed | 29 |
| 14 | odonnell | mary | F | 16 | Roman Catholic | Irish | Ontario | No Occupation Listed | 29 |
| 19 | odonnell | mary | F | 67 | Roman Catholic | Irish | Ireland | Farmers, general and nfs | 63 |
| 25 | odonnell | minnie | F | 18 | Roman Catholic | Irish | Ontario | No Occupation Listed | 63 |
| 15 | odonnell | patrick | M | 14 | Roman Catholic | Irish | Ontario | No Occupation Listed | 29 |
| 23 | odonnell | patrick | M | 26 | Roman Catholic | Irish | Ontario | Farmers, general and nfs | 63 |
| 1 | odonnell | patrick | M | 33 | Roman Catholic | Irish | Ontario | Farmers, general and nfs | 64 |
| 13 | odonnell | roger | M | 18 | Roman Catholic | Irish | Ontario | river drivers | 29 |
| 24 | odonnell | william | M | 19 | Roman Catholic | Irish | Ontario | No Occupation Listed | 8 |
| 6 | odonnell | william | M | 3 | Roman Catholic | Irish | Ontario | No Occupation Listed | 64 |
| 8 | odonnell | william | M | 48 | Roman Catholic | Irish | Ontario | Labourers nfs | 182 |
| 9 | ogilvie | george | M | 21 | Presbyterian | Scottish | Ontario | Tailors and tailoresses | 289 |
| 1 | oliver | richard | M | 55 | Methodist | English | England | river drivers | 252 |