| Norbert | | NAWR-bert (German, Polish), NAWR-bərt (English, Dutch) | German, English, Dutch, French, Hungarian, Polish, Ancient Germanic | |
| Norman | | NAWR-mən (English) | English, Ancient Germanic | |
| Oda | | O-dah (German) | German, Ancient Germanic | |
| Odalric | | - | Ancient Germanic | |
| Odila | | - | Ancient Germanic | |
| Odilia | | - | Ancient Germanic | |
| Odilie | | o-DEE-lee-ə | German (Archaic) | |
| Odilo | | - | Ancient Germanic | |
| Odo | | - | Ancient Germanic | |
| Odoacer | | o-do-AY-sər (English) | Ancient Germanic | |
| Odovacar | | o-do-VAY-kər (English) | Ancient Germanic | |
| Olaf | | O-lahf (German, Dutch) | Norwegian, Danish, German, Dutch, Polish | |
| Olga | | OL-gah (Russian), AWL-gah (Polish, German) | Russian, Ukrainian, Polish, German, Swedish, Norwegian, Danish, Icelandic, Latvian, Hungarian, Itali | |
| Oliver | | AHL-ə-vər (English), AW-lee-ver (German), O-lee-ver (Finnish) | English, German, Swedish, Norwegian, Danish, Finnish, Estonian, Serbian, Croatian, Macedonian, Czech | |
| 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 | |