| Name | Gender | Pronounced | Usage | Popularity |
|---|---|---|---|---|
| Honora | - | Irish, English | ||
| IÚIle | - | Irish | ||
| Iarfhlaith | EER-lah | Irish | ||
| Iarlaith | EER-lah | Irish | ||
| Immaculata | - | Irish | ||
| IonatÁN | - | Irish | ||
| IsibÉAl | - | Irish | ||
| Ita | - | Irish | ||
| Ivor | IE-vawr (English), EE-vawr (English) | Irish, Scottish, Welsh, English (British) | ||
| Jarlath | JAHR-lath | Irish | ||
| Kane | - | Irish | ||
| Kathleen | kath-LEEN | Irish, English | ||
| Kean | - | Irish | ||
| Keane | - | Irish | ||
| Keavy | KEE-vee | Irish, Scottish |