| # | Nombre | Orígen | Significado | Género | |
|---|---|---|---|---|---|
| 1 | O' | Irlandes | Descendent of. Irish surnames formed by prefacing O'. | M | |
| 2 | O'brian | Irlandes | Apellido. | M | |
| 3 | O'brien | Irlandes | Apellido. | M | |
| 4 | O'keefe | Irlandes | Apellido. | M | |
| 5 | O'shay | Irlandes | Apellido. | M | |
| 6 | O'shea | Irlandes | Apellido. | M | |
| 7 | Oakden | Ingles | From the oak tree valley. | M | |
| 8 | Oakes | Ingles | From the oak. | M | |
| 9 | Oakley | Ingles | From the oak - tree meadow. | M | |
| 10 | Oates | Aleman | Variante de Odo: Wealth. | M | |
| 11 | Oba | Egipcio | King. | M | |
| 12 | Obadiah | Biblico | Siervo del Seor | M | |
| 13 | Obadiah | Hebreo | Siervo/Adorador del Seor. Obadiah was the prophet who wrote the shortest book in the Old Testament. | M | |
| 14 | Obal | Biblico | Inconvenience of old age. | M | |
| 15 | Obed | Biblico | A Siervo; workman | M | |
| 16 | Obed-edom | Biblico | Siervo of Edom | M | |
| 17 | Obediah | Hebreo | Serves Dios. | M | |
| 18 | Oberon | Ingles | In A Midsummer Night's Dream, Shakespeare altered the spelling to Auberon, king del fairies, to Oberon. | M | |
| 19 | Oberon | Aleman | Noble and bear-like. In a Midsummer Night's Dream, Shakespeare altered the spelling of Auberon (King del fairies) to Oberon. | M | |
| 20 | Oberon | Shakesperiano | A Midsummer Night's Dream' King del Fairies. | M | |