| Jaka | | - | Slovene | |
| Jakob | | YAH-kawp (German), YAH-kob (Danish) | German, Swedish, Norwegian, Danish, Icelandic, Dutch, Slovene | |
| Jan (1) | | YAHN (Dutch, Swedish, Norwegian, Polish, German) | Dutch, Swedish, Norwegian, Danish, Czech, Polish, Slovene, German, Catalan | |
| Jana (1) | | YAH-nah (Dutch, German) | Czech, Slovak, Dutch, German, Slovene, Catalan | |
| Janez | | - | Slovene | |
| Janko | | - | Slovene, Croatian, Serbian, Slovak | |
| Jasmina | | - | Croatian, Serbian, Slovene, Macedonian | |
| Jasna | | - | Croatian, Serbian, Slovene, Macedonian | |
| Javor | | - | Croatian, Serbian, Slovene | |
| Jelena | | - | Serbian, Croatian, Slovene, Estonian, Latvian, Lithuanian | |
| Jelka | | - | Slovene, Croatian, Serbian | |
| Jernej | | - | Slovene | |
| Jerneja | | - | Slovene | |
| JoŠT | | - | Slovene | |
| JoŽE | | YAW-zhe | Slovene | |