| INTEREST NAME | LOCATION | DATE | EMAIL ADDRESS |
| OAKLEY | Herefordshire | All | Heather Wyman |
| O'BRIEN Morris | Old Parish | 1825-1832 | M.O'Donovan |
| ODEL/ODELL/ODLE | All | All | Whittinger |
| OLDHAM/HOLDHAM | All | pre 1890 | Kerry Gilchrist |
| OLDMAN | All | All | John Oldman |
| OLIVER | Bradnor Kington | 1800-1900 | Ros Oliver |
| OLIVER | Abbeydore Madley | All | V. Davey |
| OLIVER | Much Birch | All | V. Davey |
| OLIVER | Bromyard | Pre 1850 | Colin Stevenson |
| OLIVER | Kingsland | 19th C | Angela Golding |
| OLIVER | Pembridge | 19th-20th C | Angela Golding |
| OLIVER Elizabeth | Eye | 1825-1851 | P.Shieldhouse |
| ONIONS John | Walford | 1792-1870s | L.A-Jones |
| ORIEL Benjamin Rees | Hereford | 1895 | O.J. Vaughan |
| ORIEL George | Hereford | 1805-1815 | O.J. Vaughan |
| OSBORN(E)Eliza | Kings Norton | 1840s | Beverley Evans |
| OSELAND Edwin Ralph | Collington | 18th-19th C | Elaine Bird |
| OSELAND Sarah | Collington | 1700/1800 | Elaine Bird |
| OSEMAN | Bromyard | 1700-1820 | Adrian Fenton |
| OVEN John | Canon Pyon | 1685 on | Iris |
| OVEN John | Almely | 1660 on | C L Foley |
| OVENS William/Sarah | All | 1830 1850 | Sharon Molloy |
| OVERTON | Hereford | 1798-1819 | Dennis Overton |
| OVERTON | Leintwardine | All | Pat Powell |
| OVERTON James | All | 1798-1819 | Ginger |
| OVERTON James | Hereford | 1798-1819 | Dennis Overton |
| OWEN(S) | Leominster | 19th C | Tony Owen |
| OWEN | Warwick Hereford | 1826 | Mo Fender |
| OWEN | Birm'ham Hereford | 1853 | Mo Fender |