Irish Boy Names Starting with I

Iarlaith is the Irish form of Jarlath. It goes back to the Old Irish Iarlaithe, whose second part is usually taken to be flaith “ruler, sovereign”; the first part is of unknown meaning, so the name has no settled translation.

No. 85 for boys in Ireland in 2025, with 68 baby boys.

Iollan, also written Iollann or Illann, is an old Irish name found for men in the medieval Irish annals. Its meaning is unknown. In the Ulster Cycle of legends, Illann the Fair, a son of the former Ulster king Fergus mac Róich, fought to defend Deirdre and the sons of Uisnech after they returned under his father’s protection.

Not in Ireland's 2025 tables (fewer than three babies); last recorded in 2013.