Commune/Paroisse : Thonon-les-Bains [Haute-Savoie] 
| Patronymes | Périodes | Actes | |
|---|---|---|---|
| 1. | O'CONOR ROSS | 1877 | 1 |
| 2. | O'CONOR ROSS | 1877 | 1 |
| 3. | OBERI | 1617 | 1 |
| 4. | ODOD | 1665 | 1 |
| 5. | OGNE | 1860-1875 | 7 |
| 6. | OISEL | 1868 | 1 |
| 7. | OISEL DITE DUBOIS | 1867 | 1 |
| 8. | OLIER | 1873 | 1 |
| 9. | OLIN | 1670 | 1 |
| 10. | OLIVIER | 1646-1873 | 6 |
| 11. | OMBLET | 1698 | 1 |
| 12. | ORIOL | 1876 | 1 |
| 13. | OURCET | 1697 | 1 |
| 14. | OUTHIER | 1879 | 1 |
| 15. | OZER | 1661 | 1 |