| Ida | | IE-də (English), EE-dah (German, Swedish, Danish, Dutch, Italian) | English, German, Swedish, Norwegian, Danish, Dutch, Italian, Spanish, Portuguese, Hungarian, Slovene | |
| Ignac | | - | Slovene | |
| Ignacij | | - | Slovene | |
| Igor | | EE-gər (Russian), EE-gawr (Polish) | Russian, Polish, Slovene, Croatian, Serbian, Macedonian | |
| Ines | | - | Italian, Slovene, Croatian | |
| Irena | | ee-RE-nah (Polish), ee-RAY-nah (Dutch) | Polish, Czech, Slovene, Croatian, Serbian, Dutch, Lithuanian | |
| 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 | |
| Izidor | | - | Slovene | |
| JaŠA | | - | Slovene | |
| Jadran | | - | Croatian, Serbian, Slovene | |
| Jadranka | | - | Croatian, Serbian, Slovene | |
| Jadranko | | - | Croatian, Serbian, Slovene | |