| Janja | | - | Croatian, Serbian | |
| Janko | | - | Slovene, Croatian, Serbian, Slovak | |
| Janne (2) | | - | Danish, Norwegian | |
| Jannick | | - | Danish | |
| Jannicke | | YAHN-nik-ke (Swedish) | Norwegian, Swedish, Danish | |
| Jannik | | - | Danish | |
| Jannike | | YAHN-ni-ke (Swedish) | Norwegian, Swedish, Danish | |
| Januarius | | - | Ancient Roman | |
| Janus | | - | Roman Mythology | |
| Japik | | - | Frisian (Rare) | |
| Jaquan | | - | African American (Modern) | |
| Jaqueline | | JAK-ə-leen (English), JAK-ə-lin (English) | English (Modern), Portuguese (Brazilian) | |
| Jarl | | YAHRL (Norwegian, Swedish, Danish) | Norwegian, Swedish, Danish, Norse Mythology, Ancient Scandinavian | |
| Jarle | | - | Norwegian | |
| Jaroslavas | | - | Lithuanian | |