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O is Ireland's most romantic letter. It opens the great clan names — O'Brien, O'Connor, O'Neill — and it begins some of the most beautiful first names ever spoken: Oisín the little deer, Orla the golden princess, Oscar the deer lover.
Whether you want mythic, modern, or magnificently traditional, the O collection delivers. Every name below is genuinely Irish with its true meaning, organized so you can find your perfect one.
Heroic Irish Boy Names Starting With O
Warriors, poets, and saints — O boys' names sound like they were born in an epic.
| Name | Meaning |
|---|---|
| Owen | born of the yew tree, youthful warrior — from Eoghan |
| Eoin | God is gracious — the Irish John, pronounced 'OH-in' |
| Oscar | deer lover — the hero of Fenian legend |
| Osgar | deer lover — the grander original spelling |
| Odhran | little pale green one — pronounced 'OH-rawn', borne by saints |
| Oran | little pale green one — the sleeker variant |
| Oisín | little deer — pronounced 'ush-EEN', son of Fionn mac Cumhaill |
| Ossian | little deer — the classic anglicized form of Oisín |
| Olan | holy — short, soft, and serene |
| Oistin | little deer — another lyrical form in the Oisín family |
Golden Irish Girl Names Starting With O
Princesses and saints glow through this list — O girls' names are pure gold.
Irish Names Generator
| Name | Meaning |
|---|---|
| Orla | golden princess — short, radiant, unforgettable |
| Orlaith | golden princess — the fuller original, pronounced 'OR-la' |
| Oonagh | lamb — pronounced 'OO-na', gentle and mythic |
| Úna | lamb — the sleek modern spelling of Oonagh |
| Odharnait | little pale green one — a rare saint's name for girls |
| Ornait | little pale green one — the shorter variant |
| Olivia | olive — Latin in origin, a longtime Irish favorite |
| Ophelia | help — Greek in origin, dramatic and beautiful |
The Great O' Clan Names as First Names
No letter owns surnames like O does. These legendary clan names make first names with instant gravitas.
| Name | Meaning |
|---|---|
| Owen | born of the yew — the clan name that became a classic first name |
| O'Brien | descendant of Brian — from Ó Briain, noble and strong |
| O'Connor | descendant of Conchobar — from Ó Conchobhair, lover of hounds |
| O'Neill | descendant of Niall — from Ó Néill, the champion's line |
| O'Malley | of the great seafaring clan of the west — Grace O'Malley's people |
| O'Sullivan | dark-eyed one — from Ó Súilleabháin, spirited and proud |
| O'Reilly | valiant — from Ó Raghallaigh, full of courage |
| O'Donnell | world ruler — from Ó Domhnaill, princely and powerful |
Mythical and Historical O Names
Gods, heroes, poets, and queens — the O names of legend are Ireland's greatest hits.
| Name | Meaning |
|---|---|
| Oisín | the poet-warrior son of Fionn, who journeyed to Tír na nÓg |
| Oscar | son of Oisín, the fiercest young hero of the Fianna |
| Oonagh | the wise wife of Fionn mac Cumhaill in legend |
| Odhran | St. Odhran, the loyal charioteer-saint of legend |
| Eoghan Mór | the legendary king of Munster, 'great Eoghan' |
| Ollamh Fodhla | the legendary law-giving High King |
| Oscar Wilde | Ireland's immortal wit and playwright |
| Eoghan Rua Ó Néill | Owen Roe O'Neill, the great 17th-century general |
Frequently Asked Questions
How do you pronounce Oisín?
It is 'ush-EEN'. The 'oi' sounds like 'ush' and the fada lengthens the 'i'. It means 'little deer' and belonged to the poet son of Fionn mac Cumhaill.
What does Orla mean?
Orla (from Órlaith) means 'golden princess'. It is one of the most beloved Irish girls' names — short, luminous, and regal.
Is Oscar an Irish name?
Yes! Oscar comes from the Irish Osgar, meaning 'deer lover'. He was a hero of the Fenian legends — the Irish had him centuries before the Academy Awards.
What does the O' mean in Irish surnames?
O' comes from Ó, meaning 'descendant of'. So O'Brien means 'descendant of Brian'. It marks some of Ireland's oldest and proudest family lines.
From Oisín to Orla, O names give you mythology, royalty, and music in every syllable. They are rare enough to be distinctive and classic enough to last forever — the golden letter of Irish naming.
