| Imrich | | - | Slovak | |
| Iva (2) | | - | Czech, Slovak, Slovene | |
| Ivan | | ee-VAHN (Russian, Ukrainian), IE-vən (English) | Russian, Bulgarian, Ukrainian, Belarusian, Serbian, Croatian, Czech, Slovak, Macedonian, Slovene, En | |
| Ivana | | - | Czech, Slovak, Serbian, Croatian, Slovene, Bulgarian, Macedonian | |
| Ivanka | | - | Bulgarian, Czech, Slovak, Serbian, Croatian, Slovene | |
| Iveta | | - | Czech, Slovak | |
| Ivka | | - | Croatian, Bulgarian, Slovak, Czech | |
| Ivona | | - | Czech, Slovak, Croatian, Macedonian | |
| JÁN | | - | Slovak | |
| JÚLia | | ZHOO-lyə (Portuguese), YOO-lee-aw (Hungarian) | Portuguese, Catalan, Hungarian, Slovak | |
| JÚLius | | - | Slovak | |
| Jakub | | YAH-kuwp (Polish) | Polish, Czech, Slovak | |
| Jana (1) | | YAH-nah (Dutch, German) | Czech, Slovak, Dutch, German, Slovene, Catalan | |
| Janka | | - | Slovak | |
| Janko | | - | Slovene, Croatian, Serbian, Slovak | |