In Ireland, as elsewhere, a coat of arms is recorded for a person, not handed out to everyone who shares a surname. Irish practice does add something of its own, though: arms long associated with a Gaelic sept (a family group descended from a common ancestor) may be displayed by members of that sept as a sign of kinship, even though they are not anyone’s personal arms. Official grants come from the Chief Herald of Ireland, whose office grew out of the Ulster King of Arms (created 1552) and passed to the Irish State in 1943. For the surname itself, two of the best sources are free: Matheson’s 1894 report on Irish surnames and the 1901 and 1911 censuses.
Septs, clans and the “chief of the name”
Gaelic Ireland was organised around kin groups, usually called septs or clans. A sept shared a surname, claimed descent from a common ancestor and was usually rooted in a particular district. When the Registrar-General’s office studied Irish surnames in the 1890s, it noted that most of the country’s most common names “represent the names of Irish Clans and Septs, such as the Murphys, Kellys, Sullivans, O’Briens”.
A single surname could cover more than one sept. The same 1894 report describes several branches of the O’Sullivans: one in County Cork, “Princes of Beara”, and another, O’Sullivan Mór, Lords of Dunkerron in County Kerry.
Chiefs of the name
Each sept had a chief. For several decades in the 20th century, the Genealogical Office in Dublin gave “courtesy recognition” to men it accepted as the senior descendants of the last inaugurated chief of a Gaelic name. That practice ended in scandal. A man the office had recognised as “MacCarthy Mór” turned out to have no claim at all, and his recognition was withdrawn in July 1999. The Attorney General then advised that the office had no legal basis for recognising chiefs, and in 2003 the National Library of Ireland announced that the Chief Herald would no longer do so.
From Ulster King of Arms to the Chief Herald of Ireland
The earliest reference to an Irish herald dates from 1382. In 1552 King Edward VI created the office of Ulster King of Arms, “Herald of all Ireland”. At first its authority reached only the parts of Ireland under English control.
The last Crown-appointed Ulster King of Arms held the post until his death in 1941, and on 1 April 1943 the office passed to the Irish State, renamed the Genealogical Office and placed within the National Library of Ireland. Its first Chief Herald was Dr Edward MacLysaght. The old title went to London, where it was combined with Norroy King of Arms; that is why Northern Ireland is still covered by the College of Arms.
Today the office’s functions are set out in Section 13 of the National Cultural Institutions Act 1997. The office has normally dealt with Irish citizens and people who can document Irish ancestry, but at the time of writing (October 2026) the National Library states that it “is not accepting any new applications for grants or confirmations of arms until further notice.”
“Arms of the name”: what the Irish tradition means
In English heraldry the rule is simple: arms belong to one person and pass to that person’s descendants (see can anyone have a coat of arms?). Irish heraldry has been less rigid. Some arms recorded in Dublin, often first recorded for one individual, have long been treated as belonging to a whole sept, and the question of “clan” or “sept” arms has been argued over since the late 1940s.
The position usually linked with Edward MacLysaght draws a line between two things:
- Bearing arms: using them as your own personal arms. That right belongs to the person the arms were granted or confirmed to, and to their descendants.
- Displaying sept arms: showing the arms associated with your sept as a mark of kinship with the wider family, much as a Scottish clansman wears his chief’s crest badge (see our guide to Scottish clan crests).
Even MacLysaght, according to the Genealogical Society of Ireland, was careful to point back to the ordinary law of arms on ownership and inheritance. In practice, then, an Irish “family crest” shown under a surname is best understood as the arms of a family group, not something you own. The surname alone also isn’t enough: if your name was borne by more than one sept, or was anglicised or translated, you need genealogy to know which arms, if any, belong to your family’s story. Our guide on how to verify a coat of arms explains what to check, and coat of arms vs. family crest clears up the terms.
Ó, Mac and the anglicisation of Irish names
Most of the old Gaelic surnames carry one of two prefixes:
- Ó (written O’ in English) means “descendant” or “grandson of”. O’Toole comes from Ó Tuathail, “the descendant of Tuathal”.
- Mac (also Mc or M’) means “son of”. McDermott comes from Mac Diarmada, “son of Diarmaid”.
English law pushed hard against Gaelic naming. Matheson’s report quotes a statute of 1366 requiring every Englishman in Ireland to “be named by an English name”, and a law of 1465 ordering Irishmen living among the English in Dublin, Meath, Uriel (roughly County Louth) and Kildare to take an English surname from a town, a colour, a trade or an office, such as Sutton, White, Smith or Cooke.
Over the following centuries the prefixes were widely dropped. By the 1890s registrars found it “a matter of common occurrence” to see the same Gaelic name written with and without O or Mac in a single record. Some names were translated outright, and some people used Irish and English forms interchangeably.
The trend later reversed. Edward MacLysaght, in Irish Families (1957), described the “wholesale discarding” of the prefixes and then a reversal that began “at the beginning of the present century” under the influence of the Gaelic League. His example is striking: by Matheson’s figures there were twice as many Connells as O’Connells in 1890, while in MacLysaght’s day directories showed nine O’Connells for every Connell. For more on tracing a name through these changes, see how to trace your surname origin.
What Matheson’s 1894 report tells you
Robert E. Matheson, Assistant Registrar-General, published his Special Report on Surnames in Ireland in 1894 as an appendix to the Registrar-General’s 29th annual report. Civil registration of births had begun in 1864, so he used the 1890 births index as a sample of the whole population. His main table lists every surname with five or more births that year, with the number in each province and the counties where the name was most often found.
| Rank (1890) | Surname | Estimated bearers |
|---|---|---|
| 1 | Murphy | 62,600 |
| 2 | Kelly | 55,900 |
| 3 | Sullivan | 43,600 |
| 4–10 | Walsh, Smith, O’Brien, Byrne, Ryan, Connor, O’Neill | — |
Matheson estimated Ireland’s 1890 population at 4,717,959, so Murphys made up about 13 in every 1,000 people. For Murphy he notes that the name was “generally distributed, but the largest numbers are found in Cork, Dublin, and Wexford.” That tells you which counties to search first. The report is free to read on the Internet Archive.
The 1901 and 1911 censuses: free and remarkably complete
Ireland took a census every ten years from 1821 to 1911, but almost all of the 19th-century returns are gone. The 1861 and 1871 returns were destroyed shortly after they were taken, the 1881 and 1891 returns were pulped during the First World War, and the 1821–1851 returns were mostly lost in the 1922 fire at the Public Record Office.
The 1901 census (taken on 31 March 1901) and the 1911 census (2 April 1911) survive almost complete for all 32 counties, and the National Archives of Ireland publishes both online free of charge. They are the original household forms, filled in and signed by the head of each household, and they record:
- name, age, sex and relationship to the head of household
- religion, occupation and marital status
- county or country of birth
- literacy and ability to speak Irish
- in 1911 only, for married women: years married, children born alive and children still living
The census of 1926, the first of the Irish Free State (26 counties), was closed for 100 years and is now being released on the same website. Read alongside Matheson’s tables, the census can place a surname in its home county and show the household an emigrant left behind. If the family later crossed to America, our article on whether names were changed at Ellis Island covers the next chapter.
See the arms recorded for your surname →
Sources
- National Library of Ireland, “Office of the Chief Herald of Ireland”: https://nli.ie/office-chief-herald
- Robert E. Matheson, Special Report on Surnames in Ireland (Dublin: HMSO, 1894), Internet Archive: https://archive.org/details/op1253043-1001
- National Archives of Ireland, “Search the Census”: https://nationalarchives.ie/collections/search-the-census/
- National Archives of Ireland, “History of Irish census records”: https://nationalarchives.ie/collections/search-the-census/about-the-census-collections/history-of-irish-census-records/
- National Archives of Ireland, “Census 1901”: https://nationalarchives.ie/collections/search-the-census/about-the-census-collections/census-1901/
- Seán J. Murphy, “The talented Mr MacCarthy ‘Mór'”, History Ireland 19:3 (2011): https://historyireland.com/the-talented-mr-maccarthy-mor/
- Genealogical Society of Ireland, “Heraldry”: https://familyhistory.ie/heraldry-ireland/
- “The Dublin Vertigo”, Dublin Review of Books (quoting E. MacLysaght, Irish Families, 1957): https://drb.ie/blog/the-dublin-vertigo/
- François Velde, “Heraldry in Ireland”, Heraldica: https://heraldica.org/topics/national/ireland.htm
Frequently asked questions
Is there an Irish coat of arms for my surname?
Not in the sense of one coat of arms owned by everyone with the name. Arms are recorded for individuals, but Irish practice also links certain arms to a Gaelic sept, and members of that sept may display them as a sign of kinship. Because one surname can belong to several unrelated families, you need to know which family your line comes from.
What is the difference between displaying sept arms and bearing arms?
Bearing arms means using them as your own personal arms, a right that belongs to the person they were granted or confirmed to and to that person’s descendants. Displaying sept arms means showing the arms associated with your wider family group as a mark of belonging. The distinction is associated with Edward MacLysaght, the first Chief Herald of Ireland, and it is still debated among heraldists.
Can I apply to the Chief Herald of Ireland for a coat of arms?
The office has normally dealt with Irish citizens and people who can document Irish ancestry. However, the National Library of Ireland currently states that the Office of the Chief Herald is not accepting new applications for grants or confirmations of arms until further notice, so check its page before planning anything.
Why did so many Irish families drop the O or Mac?
The prefixes were widely dropped from about the 18th century onward, and registrars in the 1890s still found the same names written with and without them in a single record. Edward MacLysaght described a reversal that began in the early 20th century under the influence of the Gaelic League; he noted that in 1890 there were twice as many Connells as O’Connells, while in his day O’Connells outnumbered Connells nine to one.
Are the 1901 and 1911 Irish censuses really free?
Yes. The National Archives of Ireland publishes both censuses online free of charge, with searchable transcriptions and images of the original household forms. They are the only complete surviving Irish censuses from before independence, and the 1926 census of the Irish Free State is now being released on the same site.