Naming guide
What makes a great Irish name
Irish names come in two layers: the Irish-language form and the anglicized form most of the world knows. Between the 17th and 19th centuries, when English was the language of courts and records, clerks wrote Gaelic names down by sound or swapped them for English names that seemed close. Tadhg became Timothy, Donncha became Denis, Diarmuid became Dermot or Jeremiah, and Ó Súilleabháin became O'Sullivan or plain Sullivan. The Gaelic Revival, driven from 1893 by the Gaelic League (Conradh na Gaeilge), brought Irish spellings back into fashion, and many families restored the O and Mac they had dropped.
Irish first names come from three main sources. Saints gave Pádraig, Bríd, Colm, Ciarán and Breandán. Mythology gave Fionn, Oisín, Niamh, Méabh, Deirdre and Áine. The 20th century added revived or new names such as Saoirse (freedom), Aisling (a dream or vision) and Fiadh (wild, or deer); Saoirse and Fiadh now rank among the most popular girls' names in Ireland.
Irish surnames mark descent. Ó means grandson or descendant, so the O'Briens descend from Brian Boru, the high king killed at the Battle of Clontarf in 1014. Mac means son, so MacCarthy is son of Cárthach. In Irish, surnames change with gender: a daughter uses Ní instead of Ó and Nic instead of Mac, and the next consonant usually softens. Seán Ó Briain's sister is Aoife Ní Bhriain, and a married woman may style herself Bean Uí Bhriain, Mrs O'Brien. Norman families arriving from 1169 added Fitzgerald, Burke, Roche, Power and Walsh (Breathnach, the Welshman), and they assimilated so fully that they became known as more Irish than the Irish themselves.
Irish spelling looks hard, but it follows a few consistent rules:
- bh and mh usually sound like v: Siobhán (shiv-AWN), Niamh (NEEV), Méabh (MAYV)
- dh and gh are often silent: Tadhg (TYGE), Eoghan (OH-in), Fiadh (FEE-a)
- th is a light h or silent: Cathal (KA-hal), Bláthnaid (BLAW-nid)
- s beside e or i sounds like sh: Seán (SHAWN), Róisín (roe-SHEEN), Saoirse (SEER-sha)
- ao sounds like ee: Aoife (EE-fa), Caoimhe (KEE-va), Naoise (NEE-sha)
- ch is throaty, as in the Scottish loch: Donncha (DUN-uh-kha), Fiachra (FEE-akh-ra)
- The fada, the accent mark, lengthens a vowel and can change the meaning: Seán is a name, but sean means old
Irish name ideas
Irish girl names
- Aoife (EE-fa): beauty and radiance
- Saoirse (SEER-sha): freedom, first used in the 1920s
- Caoimhe (KEE-va): gentle and precious
- Róisín (roe-SHEEN): little rose
- Sadhbh (SIVE, rhymes with five): sweetness, the mother of Oisín in legend
- Bláthnaid (BLAW-nid): little flower
- Muireann (MWIR-in): sea-white, sea-fair
- Fiadh (FEE-a): wild, or deer
Irish boy names
- Tadhg (TYGE): poet or philosopher
- Oisín (uh-SHEEN): little deer, the poet son of Fionn
- Cian (KEE-un): ancient, enduring
- Ruairí (ROO-ree): red king
- Darragh (DAR-a): oak
- Odhrán (OH-rawn): little pale one
- Fiachra (FEE-akh-ra): raven
- Lorcan (LUR-kan): little fierce one
Irish surnames with Ó and Mac
- Ó Súilleabháin, O'Sullivan: linked to súil, eye, a great Cork and Kerry name
- Mac Cárthaigh, MacCarthy: son of Cárthach, the loving one
- Ó Murchú, Murphy: from Murchadh, sea warrior
- Mac Conmara, MacNamara: son of the hound of the sea, from Clare
- Ó Dónaill, O'Donnell: the ruling family of Tír Chonaill in Donegal
- Ó Flaithbheartaigh, O'Flaherty: the lords of west Connacht
- Ó Gallchóir, Gallagher: a Donegal name often glossed as foreign helper
Norman Irish last names
- Fitzgerald: son of Gerald, the Geraldines of Kildare and Desmond
- Burke: from the Norman de Burgh, powerful across Connacht
- Walsh: Breathnach in Irish, the Welshman
- Joyce: Welsh-Norman settlers who gave their name to Joyce Country in Galway
- Power: from le Poer, rooted in Waterford
- Roche: from de la Roche, the rock, strong in Cork and Wexford
How to create your own Irish name
- Match the surname to a province. Families clustered for centuries: Munster has O'Sullivan, MacCarthy, O'Brien and Murphy; Leinster has Kavanagh, Byrne, O'Toole and Doyle; Connacht has O'Flaherty, Joyce, O'Malley and Burke; Ulster has O'Neill, O'Donnell, Gallagher and Doherty.
- Choose a spelling register. A name can be fully Irish (Pádraig Ó Briain), fully anglicized (Patrick O'Brien), or mixed in the modern way (Saoirse Murphy). Pick one on purpose, because the choice says something about the family's politics, schooling or generation.
- Get the gender right in Irish forms. Ó becomes Ní and Mac becomes Nic, and the following consonant takes an h: Ó Conaill becomes Ní Chonaill, Mac Mathúna becomes Nic Mhathúna. Names that start with a vowel, l, n or r do not change, so Ó Néill becomes Ní Néill.
- Pick an era. Medieval Ireland had names like Gormlaith, Mór, Donnchadh and Toirdhealbhach. Nineteenth-century records are full of Bridget, Honora, Johanna, Patrick and Michael. Modern birth notices favor Fiadh, Éabha, Oisín and Cillian.
- Use pet forms. The ending -ín makes a diminutive, as in Róisín (little rose) and Pádraigín, and everyday nicknames like Peig for Margaret or Nóra for Honora make a character feel lived in.
Tips for using Irish names in your game or story
Give readers a pronunciation anchor once. The first time Caoimhe or Tadhg appears, let another character say it or add a short note, then trust the reader. Respelling a name phonetically every time is tiring.
Keep the fadas. Irish readers notice when Seán becomes Sean or Róisín becomes Roisin, and in some names the accent changes the meaning entirely.
Use the traditional naming pattern for families. Irish parents often named the first son after the paternal grandfather, the second son after the maternal grandfather, the first daughter after the maternal grandmother and the second daughter after the paternal grandmother. This explains why cousins in historical fiction so often share names.
Do not confuse Irish with Scottish. Both use Mac and share many names, but the O prefix is almost entirely Irish, and spellings differ: the Irish Séamus corresponds to the Scottish Gaelic Seumas, the source of Hamish.
For Celtic-inspired fantasy, mythic names such as Niamh, Fiachra, Bébhinn or Naoise add depth, but avoid giving a headline hero's name like Cú Chulainn to a minor character, since Irish readers will recognize it instantly. Skip stage-Irish clichés entirely; a real name from the right county will always read better than a joke about shamrocks.