Residents of Dunnville, T-V — Sub-district I, surnames O (1881 Census)
| # | Surname | Given | Sex | Age | Religion | Origin | Birthplace | Occupation | HH |
| 5 | obrien | thomas | M | 81 | Roman Catholic | Irish | Ireland | Labourers nfs | 240 |
| 19 | oglisby | ida | F | 24 | Wesleyan Methodist | English | Ontario | No Occupation Listed | 315 |
| 21 | oglisby | john | M | 1 | Wesleyan Methodist | English | Ontario | No Occupation Listed | 315 |
| 20 | oglisby | robert | M | 2 | Wesleyan Methodist | English | Ontario | No Occupation Listed | 315 |
| 18 | oglisby | wellengton | M | 25 | Baptist | English | Ontario | Railway builders, workers and labourers | 315 |
| 17 | oldfield | james | M | 35 | Anglican | Irish | Ontario | No Occupation Listed | 98 |
| 4 | oldfield | john | M | 24 | Anglican | English | Ontario | Clerk, nfs | 210 |
| 1 | oldfield | mariah | F | 58 | Anglican | English | England | No Occupation Listed | 210 |
| 2 | oldfield | mary | F | 38 | Anglican | English | Ontario | No Occupation Listed | 210 |
| 3 | oldfield | thomas | M | 29 | Anglican | English | Ontario | Clerk, nfs | 210 |
| 10 | oldfield | wm | M | 20 | Anglican | English | Ontario | No Occupation Listed | 54 |
| 10 | oliver | james | M | 28 | Presbyterian | Irish | Ontario | No Occupation Listed | 136 |
| 7 | orme | george | M | 9 | Anglican | English | Ontario | No Occupation Listed | 159 |
| 6 | orme | john | M | 15 | Anglican | English | Ontario | No Occupation Listed | 159 |
| 2 | orme | lousia | F | 44 | Anglican | English | England | No Occupation Listed | 159 |
| 10 | orme | lousia | F | 3 | Anglican | English | Ontario | No Occupation Listed | 159 |
| 4 | orme | mariah | F | 19 | Anglican | English | Ontario | No Occupation Listed | 159 |
| 5 | orme | mary | F | 17 | Anglican | English | Ontario | No Occupation Listed | 159 |
| 9 | orme | minnie | F | 5 | Anglican | English | Ontario | No Occupation Listed | 159 |
| 3 | orme | nellie | F | 21 | Anglican | English | Ontario | No Occupation Listed | 159 |
| 1 | orme | thomas | M | 49 | Anglican | English | United States | Carpenters | 159 |
| 8 | orme | thomas | M | 7 | Anglican | English | Ontario | No Occupation Listed | 159 |
| 7 | overholt | albert | M | 8 | Baptist | German | Ontario | No Occupation Listed | 111 |
| 4 | overholt | alice | F | 18 | Baptist | German | Ontario | No Occupation Listed | 111 |
| 7 | overholt | alice | F | 20 | Anglican | Irish | Ontario | Servants nfs | 130 |
| 6 | overholt | edward | M | 17 | Baptist | German | Ontario | No Occupation Listed | 111 |
| 2 | overholt | elizabeth | F | 44 | Baptist | English | England | No Occupation Listed | 111 |
| 1 | overholt | henry | M | 59 | Baptist | German | Ontario | No Occupation Listed | 111 |
| 5 | overholt | henry | M | 21 | Baptist | German | Ontario | No Occupation Listed | 111 |
| 3 | overholt | mary | F | 10 | Baptist | German | Ontario | No Occupation Listed | 111 |
| 8 | overholt | maud | F | 4 | Baptist | German | Ontario | No Occupation Listed | 111 |