| Surname | Individuals |
|---|---|
|
O'Brien
|
2 |
|
O'Connor
|
1 |
|
O'Donnell
|
7 |
|
O'Sullivan
|
1 |
|
Oaks
|
1 |
|
Oates
|
1 |
|
Obele
|
1 |
|
Oberdick
|
4 |
|
Ockford
|
5 |
|
Odell
|
5 |
|
Ogan
|
12 |
|
Ogden
|
1 |
|
Ohlman
|
1 |
|
Oldfield
|
1 |
|
Oldham
|
1 |
|
Olds
|
2 |
|
Oliver
|
10 |
|
Olmsted
|
1 |
|
Olson
|
1 |
|
Oman
|
2 |
|
Orchard
|
4 |
|
Orgy
|
1 |
|
Ormashaw
|
1 |
|
Orr
|
1 |
|
Orson
|
1 |
|
Orton
|
6 |
|
Osborn
|
2 |
|
Osborne
|
3 |
|
Osman
|
1 |
|
Ouderkirk
|
3 |
|
Overbaugh
|
1 |
|
Owen
|
1 |
|
Owen-Conway
|
1 |
|
Oxley
|
1 |