| InÊS | | ee-NESH | Portuguese | |
| Iolanda | | - | Italian, Portuguese, Romanian | |
| 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 | |
| Iria | | - | Portuguese, Galician | |
| Isabel | | ee-sah-BEL (Spanish), IZ-ə-bel (English), ee-za-BEL (French), ee-zah-BEL (German) | Spanish, Portuguese, English, French, German | |
| Isabela | | ee-sah-BEL-ah (Spanish) | Spanish, Portuguese, Romanian | |
| Isaura | | ee-SOW-rah (Spanish) | Portuguese, Spanish, Late Roman | |
| 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 | |
| Ivo (1) | | EE-vo (German, Dutch, Italian), EE-fo (German), EE-voo (Portuguese) | German, Dutch, Italian, Portuguese, Czech, Ancient Germanic | |
| Izabel | | - | Portuguese (Brazilian) | |
| JÔNatas | | - | Portuguese | |
| JÚLia | | ZHOO-lyə (Portuguese), YOO-lee-aw (Hungarian) | Portuguese, Catalan, Hungarian, Slovak | |
| JacÓ | | - | Portuguese | |
| Jacinta | | hah-THEEN-tah (Spanish), hah-SEEN-tah (Latin American Spanish) | Spanish, Portuguese | |
| Jacinto | | hah-THEEN-to (Spanish), hah-SEEN-to (Latin American Spanish) | Spanish, Portuguese | |