| Olexiy | | - | Ukrainian | |
| Olga | | OL-gah (Russian), AWL-gah (Polish, German) | Russian, Ukrainian, Polish, German, Swedish, Norwegian, Danish, Icelandic, Latvian, Hungarian, Itali | |
| Olgica | | - | Macedonian, Serbian | |
| Olha | | - | Ukrainian | |
| Olimpia | | aw-LEEM-pyah (Polish) | Italian, Spanish, Romanian, Polish, Hungarian | |
| OlivÉR | | O-lee-vayr | Hungarian | |
| Oliva | | - | Late Roman | |
| Oliver | | AHL-ə-vər (English), AW-lee-ver (German), O-lee-ver (Finnish) | English, German, Swedish, Norwegian, Danish, Finnish, Estonian, Serbian, Croatian, Macedonian, Czech | |
| Olivera | | - | Serbian, Croatian, Macedonian | |
| Olivia | | ə-LIV-ee-ə (English), o-LEE-vyah (Italian, Spanish), o-LEE-vee-ah (German), O-lee-vee-ah (Finnish) | English, Italian, Spanish, German, Finnish, Swedish, Norwegian, Danish | |
| Oliviero | | o-lee-VYE-ro | Italian | |
| Olja | | - | Serbian | |
| Olubunmi | | - | Western African, Yoruba | |
| Oluchi | | - | Western African, Igbo | |
| Oluf | | - | Danish | |