| Isolda | | i-ZOL-də (English), i-SOL-də (English) | Arthurian Romance | |
| Isolde | | i-ZOL-də (English), i-SOL-də (English), ee-ZAWL-du (German) | English (Rare), German, Arthurian Romance | |
| IstvÁN | | - | Hungarian | |
| IvÁN | | - | Spanish, Hungarian | |
| Izabella | | ee-zah-BEL-lah (Polish) | Hungarian, Polish | |
| IzidÓRa | | - | Hungarian (Rare) | |
| IzsÁK | | EE-zhahk | Hungarian | |
| JÁKob | | - | Hungarian | |
| JÁNos | | YAH-nosh | Hungarian | |
| JÁZmin | | YAHZ-meen | Hungarian | |
| JÓSka | | - | Hungarian | |
| JÓZsef | | YO-zhef | Hungarian | |
| JÓZsi | | YO-zhee | Hungarian | |
| JÓZsua | | YO-zhoo-aw | Hungarian | |
| JÚLia | | ZHOO-lyə (Portuguese), YOO-lee-aw (Hungarian) | Portuguese, Catalan, Hungarian, Slovak | |