| # | Name | Origin | Meaning | Gender | |
|---|---|---|---|---|---|
| 1901 | Odelette | Greek | Little singer. | F | |
| 1902 | Odelle | Greek | Harmonious. | F | |
| 1903 | Odessa | Greek | Wrathful. | F | |
| 1904 | Odysseia | Greek | Wrathful. | F | |
| 1905 | Odysseus | Greek | Wrathful. | M | |
| 1906 | Oedipus | Greek | Swollen foot. | M | |
| 1907 | Oeneus | Greek | King of Calydon. | M | |
| 1908 | Oenomaus | Greek | Son of Ares. | M | |
| 1909 | Oenone | Greek | Lover of Paris. | F | |
| 1910 | Oighrig | Greek | Well spoken. | F | |
| 1911 | Oighrig | Greek | Well spoken. | M | |
| 1912 | Oleisia | Greek | Protector of man. | F | |
| 1913 | Olena | Greek | Light. | F | |
| 1914 | Oles | Greek | Defender of man. | M | |
| 1915 | Olexa | Greek | Defender of mankind. Feminine of Alexander. | F | |
| 1916 | Olina | Greek | Light. | F | |
| 1917 | Olympe | Greek | From Olympus. | F | |
| 1918 | Olympia | Greek | From the home of the gods (Olympus). | F | |
| 1919 | Omphale | Greek | A queen of Lydia. | F | |
| 1920 | Onella | Greek | Light. | F | |