| Name | Pronunciation | Meaning | English Spelling | Gender |
|---|---|---|---|---|
| Iarlaithe, Iarlaith | (YAR-la) | M | ||
| Iarlug, Iarlugh | (YAR-loo) | M | ||
| Ibor, Iobhar | (EEV-ar) | yew | Ivor, Ivan | M |
| Idnat, Iodhnait, Íonait | (EEN-it) | Enat, Enid | F | |
| Iffernán, Ifearnán | (IF-fer-nawn) | Heffernan | M | |
| Illann, Iollann | (OO-lawn) | M | ||
| Ímar, Íomhar | (AI-var) | Ivor, Ifor | M | |
| Imchad, Iomchadh | (UM-ach-a) | M | ||
| Indrechtach, Ionnrachtach | (UN-racht-ach) | M | ||
| Ioseph | (YO-sef) | borrowing of Biblical Joseph | M | |
| Ír, Íor | (EER) | M | ||
| Irél, Irial | (er-EEL) | M | ||
| Íte, Íde | (EE-da, EE-ta) | Ita | F | |
| Iuchra | (UCH-ra) | F |