| Iason | | - | Greek Mythology, Ancient Greek, Greek, Biblical Greek, Biblical Latin | |
| 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) | |
| 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) | |
| Isokrates | | - | Ancient Greek | |