| Isaac | | IE-zək (English) | English, Jewish, Biblical, Biblical Latin | |
| Isabel | | ee-sah-BEL (Spanish), IZ-ə-bel (English), ee-za-BEL (French), ee-zah-BEL (German) | Spanish, Portuguese, English, French, German | |
| Isabella | | ee-zah-BEL-lah (Italian), iz-ə-BEL-ə (English) | Italian, German, English, Swedish, Norwegian, Danish, Dutch, Romanian | |
| Isabelle | | ee-za-BEL (French), IZ-ə-bel (English), ee-sah-BEL-lə (Dutch) | French, English, German, Dutch | |
| Isador | | IZ-a-dawr | English (Rare) | |
| Isadora | | - | English | |
| Isadore | | IZ-ə-dawr | English | |
| Isaiah | | ie-ZAY-ə (English), ie-ZIE-ə (English) | English, Jewish, Biblical | |
| Isbel | | IZ-bel | English (Rare) | |
| Isebella | | iz-ə-BEL-ə | English (Rare) | |
| Iseut | | - | Medieval English | |
| Isiah | | ie-ZIE-ə | English | |
| Isidora | | ee-see-DHO-rah (Spanish), ee-zee-DO-rah (Italian), iz-i-DAWR-ə (English) | Serbian, Macedonian, Spanish, Portuguese, Russian (Rare), Italian (Rare), English (Rare), Ancient Gr | |
| Isidore | | IZ-i-dawr (English), ee-zee-DOR (French) | English, French, Georgian, Jewish | |
| Isolde | | i-ZOL-də (English), i-SOL-də (English), ee-ZAWL-du (German) | English (Rare), German, Arthurian Romance | |