| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| JÚLia | ZHOO-lyə (Portuguese), YOO-lee-aw (Hungarian) | Portuguese, Catalan, Hungarian, Slovak | ||
| 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 | ||
| Jaume | ZHOW-mə | Catalan | ||
| Jaumet | - | Catalan | ||
| Joan (2) | joo-AHN (Catalan), zhoo-AHN (Catalan) | Catalan, Occitan | ||
| Joana | - | Portuguese, Catalan | ||
| Joaquim | - | Portuguese, Catalan | ||
| Joaquima | - | Catalan | ||
| Jordi | - | Catalan | ||
| Josep | - | Catalan |