| Ingulf | | - | Ancient Germanic | |
| Ingvildr | | - | Ancient Scandinavian | |
| Iodocus | | - | Ancient Celtic (Latinized) | |
| Iovianus | | - | Ancient Roman | |
| Iovita | | - | Ancient Roman | |
| Irenaeus | | - | Ancient Greek (Latinized) | |
| Irene | | ie-REEN (English), ie-REE-nee (English), ee-RE-ne (Italian), EE-re-ne (Finnish), ee-RE-nu (German) | English, Italian, Spanish, Portuguese, Swedish, Norwegian, Danish, Finnish, German, Ancient Greek (L | |
| Ireneus | | - | Ancient Greek (Latinized) | |
| Irma | | EER-mah (German, Finnish), UR-mə (English) | German, English, Dutch, Finnish, Spanish, Italian, Georgian, Lithuanian, Hungarian (Rare), Ancient G | |
| Isa (3) | | - | Frisian, Ancient Germanic | |
| Isbrand | | - | Ancient Germanic | |
| Ishild | | - | Ancient Germanic (Hypothetical) | |
| 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 | |
| Isidoros | | - | Ancient Greek | |
| Isocrates | | - | Ancient Greek (Latinized) | |