| Isabelle | | ee-za-BEL (French), IZ-ə-bel (English), ee-sah-BEL-lə (Dutch) | French, English, German, Dutch | |
| Isaia | | - | Italian | |
| Isaija | | - | Serbian, Macedonian | |
| Isak | | EE-sahk | Swedish, Norwegian, Danish | |
| Isamu | | ee-sah-moo | Japanese | |
| Isaura | | ee-SOW-rah (Spanish) | Portuguese, Spanish, Late Roman | |
| Isaurus | | - | Late Roman | |
| Isay | | - | Russian | |
| Isbrand | | - | Ancient Germanic | |
| Iset | | - | Egyptian Mythology | |
| Iseul | | - | Korean | |
| Iseult | | i-SOOLT (English), i-ZOOLT (English), EE-səlt (English) | Arthurian Romance | |
| Isha | | - | Indian, Hindi, Marathi, Hinduism | |
| Ishani | | - | Indian, Hindi | |
| Ishild | | - | Ancient Germanic (Hypothetical) | |