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Ó Súilleabháin
Arms of O'Sullivan
Parent houseEóganachta
CountryKingdom of Desmond
Kingdom of Ireland
FounderSuilebhan mac Maolura
Final rulerDonal Cam O'Sullivan Beare
Cadet branchesO'Sullivan Mór
O'Sullivan Beare
O’Sullivan MacCragh

O'Sullivan (Irish: Ó Súilleabháin, Súileabhánach) is an Irish Gaelic clan based most prominently in what is today County Cork and County Kerry. The surname is associated with the southwestern part of Ireland, and was originally found in County Tipperary and Kerry before the Anglo-Norman invasion. It is the third most numerous surname in Ireland. Due to emigration, it is also common in Australia, North America, Britain, and the rest of the world.

According to traditional genealogy, the O’Sullivans were descended from the ancient Eóganacht Chaisil sept of Cenél Fíngin, the founder of the clan who was placed in the 9th century, eight generations removed from Fíngen mac Áedo Duib, king of Cashel or Munster from 601 to 618. Later, they became the chief princes underneath their close kinsmen, the MacCarthy dynasty, in the small but powerful Kingdom of Desmond, successor of Cashel/Munster. The last independent ruler of the clan was Donal Cam O'Sullivan Beare, who was defeated in the Nine Years' War of 1594–1603.

Etymology and orthography[edit]

Ó Súilleabháin consists of ó (Old Irish úa) "grandchild, descendant", and the masculine genitive case of Súileabhán, viz. Súileabhán's grandchild/descendant. The female form in Modern Irish is Ní Shúileabhán; "ní" is the shortened form of iníon uí, iníon "daughter", , the genitive of ó "grandchild, descendant".

The etymology of the given name is uncertain. In his book titled The Surnames of Ireland, genealogist Edward MacLysaght states that “while there is no doubt that the basic word is súil (eye) there is a disagreement as to the meaning of the last part of the name.” It is interpreted as súildubhán ⇄ “little dark-eyed one” by Woulfe in Sloinnte Gaedheal is Gall, from súil ⇄ "eye," dubh ⇄ "dark/black," and combined with the diminutive suffix -án. Other suggested etymologies include "one-eyed" and "hawk-eyed."[citation needed]

The original bearer of the name, one Suilebhan mac Maolura, is recorded in legendary Irish genealogy as belonging to the 8th generation after Fíngen mac Áedo Duib, and placed in the 9th century.[1]

MacLysaght lists Mac Criomhthain (MacCrohan) and Mac Giolla Chuda (MacGillycuddy) as notable branches of the Súileabhánaigh in County Kerry.

O'Sullivan is the regular anglicization of the Irish name. Less common spelling variants of the name include: Sullavan, Sullivant, Sillivant, Silliphant, and Sillifant.

Naming conventions[edit]

Male Daughter Wife (Long) Wife (Short)
Ó Súilleabháin[2] Ní Shúilleabháin Bean Uí Shúilleabháin Uí Shúilleabháin


Some O'Sullivans in the midlands and south Ulster were originally (O) Sullahan (from Ó Súileacháin, probably from súileach, quick-eyed, according to MacLysaght). This surname has now almost entirely changed to Sullivan.


Legendary genealogy[edit]

According to the genealogy recorded in the 17th-century Leabhar na nGenealach, the O'Sullivan clan claimed descent from the Eóganachta dynasty of the Kings of Munster (and via them, ultimately, from Milesius, Fénius Farsaid and Adam). The legendary founder of the clan, Suilebhan mac Maolura, is recorded as born in 862[citation needed] as a descendant from the line of the kings of Munster, of the Eóganachta dynasty, eight generations after Fíngen mac Áedo Duib (d. 618).[1]

Medieval period[edit]

Following the Norman invasion of Ireland in 1169–71, Norman incursions into Munster were made in the 1180s. The O'Sullivan clan was forced from their original homeland in County Tipperary by the Normans in 1193.[citation needed] Dunlong son of Giolla Mochoda in 1196 from Tipperary to County Kerry.[citation needed]

They divided into several branches and the two main ones are:

  • O'Sullivan Mór (Mór indicating larger or greater) in south Kerry, and
  • O'Sullivan Beare in the Beara Peninsula, West Cork and South Kerry

The cadet branch of the O'Sullivan Mór dynasty is McGillycuddy of the Reeks (Mac Giolla Mochuda). Of the O'Sullivans Beare the cadet branch was the sept Mac Fineen Duff (Mac Fíghin Dúibh), now thought to be defunct.

The "Beare" suffix came from the Beara peninsula that was named for the Spanish princess Bera, the wife of the first King of Munster. They continued to be harassed by the Normans and so allied themselves with the McCarthys and the O'Donoghues.[citation needed]

The three clans defeated the Normans in 1261 at the battle of Caisglin near Kilgarvan, just north of Kenmare. They were again victorious the following year. These two battles settled the boundaries between the Normans of north Kerry (the FitzGeralds) and the three Gaelic families of south Kerry and west Cork.[citation needed]

Early modern period[edit]

The O'Sullivan Beare clan was further divided in 1592. When Dónal O'Sullivan, the chieftain, was slain in 1563 his son of the same name was but a child two years of age. The Irish laws of Tanistry required that the title of chieftain be passed on to the most capable of the dead chief's family. As a result, the clan decided that Owen, one of the brothers of the dead chief, would take over control of the clan and become Lord of Beare and Bantry. Owen acknowledged the English crown and was knighted by Queen Elizabeth.

In 1587 Dónal, now twenty-six years old, decided to claim leadership of the clan. He petitioned the authorities in Dublin, using primogeniture as the basis for his claim, whereby the oldest son should inherit his father's title regardless of his age at the time of his father's death. The English Commission in Dublin was receptive to his argument since they preferred to have the English procedure followed throughout Ireland. In addition Sir Owen had lost influence in Dublin due to implication in the Desmond Rebellion. The Commission found in favor of Dónal, who was now The O'Sullivan Beare. Sir Owen had to be content with Whiddy island and part of Bantry. He died the following year and was succeeded by his son, another Sir Owen.

The O'Sullivans and other clans provided shelter to 12-year-old Gerald FitzGerald when troops sought to capture him as the last heir to the Earlship of Desmond.

In the late 1590s, it was the Sullivan Mor clan and their close allies the McSweenys who bore the brunt of the fighting with the English forces.[citation needed] Donal, however, held the O'Sullivan Beare clan, held back from the fighting until the O'Donnells and O'Neills of Ulster entered the campaign.

After 1600[edit]

By the year 1600 all of Munster was in a turmoil. As retribution for their support of the Desmond rebellion, the Munster clans lost over 500,000 acres (2,000 km2) of their land to English settlers. When the Earl of Clancarty died in 1596 his lands were parceled out as well to settlers.

King Philip III of Spain agreed to send help to his co-religionists in Ireland under the command of Don Juan D'Aquila. Rather than landing in Ulster, as suggested by O'Neill, the Spanish forces landed at Kinsale in County Cork to avoid encountering English warships in the Irish Sea. The war weary and decimated Munster clans had difficulty mustering an army to join the Ulster and Spanish forces. The Spanish were given the responsibility of forming the garrisons for the castles of the O'Driscolls and the O'Sullivans so as to free the Irish troops for the battles to come. The rest of the four thousand Spanish soldiers remained at Kinsale to await the arrival of the Ulster forces.

Donal O'Sullivan Beare was given command of the Munster forces, which consisted mainly of soldiers of his clan and those of the O'Driscolls, McSweeneys, and O'Connor Kerry. Daniel O'Sullivan Mor could only contribute token support because of the losses he had sustained in the previous years. Dónal marched to Kinsale with an army of one thousand men. He sent a letter to King Philip swearing allegiance to him as his sovereign. The letter was intercepted by English agents and was later used as reason for denying him pardon.

On 24 December 1601 at the coming of dawn the battle began. It was over in a matter of hours. It was a resounding defeat for the Irish forces. This was due in large part to the reluctance of the Spanish troops to leave the protection of the walled city of Kinsale and join the battle until it was over. O'Neill retreated back to Tyrone with his battered troops. O'Donnell handed over command of his soldiers to his brother and embarked for Spain to plead for more help from King Philip. General Aquila sued for peace and Lord Mountjoy, commander of the English, was only too happy to accept his request. Aquila agreed to surrender the castles his troops were defending. This meant that the O'Sullivans and the O'Driscolls had to fight the Spanish to regain their castles. Donal O'Sullivan wrote to King Philip complaining about the behavior of Aquila. When Aquila returned to Spain he was held in contempt by King Philip and put under house arrest.

Many of the O'Sullivan clan's non-combatants were sent to the island of Dursey to keep them out of harm's way. An English force led by a John Bostock attacked the small garrison guarding the island. They butchered the entire population of the island, women, children, and the garrison. They cast their bodies, some while they were still alive, onto the rocks below the cliff overlooking the sea.

The O'Sullivan Beare principal fortress, Dunboy Castle, was destroyed in the Siege of Dunboy in 1602 and its garrison was put to death by hanging.

Dónal O'Sullivan and approximately one thousand followers consisting of four hundred soldiers and the rest civilians began a journey to Leitrim to the castle of his friend Ó Ruairc (O'Rourke). He believed that he could hold out longer amongst his northern allies, the O'Donnells and O'Neills.

Carew declared them outlaws and decreed that anyone that aided them would be dealt with as outlaws as well. Throughout the 300-mile (480 km) trek they were attacked by English forces and Irish that were loyal to Elizabeth. The countryside had been ravaged by war and famine; the people along the way were trying to stay alive themselves. They could ill afford to provide any aid or food. They began the march on 31 December 1602. A detailed account of the march is provided by Philip O'Sullivan Beare, a nephew of Dónal O'Sullivan.[year needed]

Notable people named O'Sullivan[edit]

Notable people named Sullivan[edit]

See also[edit]


  1. ^ a b Irish Family History, Dublin, 1865 p. 237. Genealogy: Óengus mac Nad Froích (d. 489, first Christian king of Munster), Feidlimid mac Óengusa ("Felim"), "Criomthan", "Hugh Dubh", Fíngen mac Áedo Duib ("Flan", d. 618), Seachnusa, Fiacha Laoch, Flan, Dubh-Jonracht, Murrogh, Eigherein, Maolura, Suilebhan.
  2. ^ "Ó Súilleabháin". Sloinne. 5 December 2015.
  • Byrne, Francis J., Irish Kings and High-Kings. Four Courts Press. 3rd edition, 2001.
  • Charles-Edwards, T.M., Early Christian Ireland. Cambridge University Press. 2000.
  • Cronnelly, Richard F., Irish Family History Part II: A History of the Clan Eoghan, or Eoghanachts. Dublin: 1864.
  • Curley, Walter J.P., Vanishing Kingdoms: The Irish Chiefs and their Families. Dublin: Lilliput Press. 2004.
  • Duffy, Seán (ed.), Medieval Ireland: An Encyclopedia. Routledge. 2005.
  • Koch, John T. (ed.), Celtic Culture: A Historical Encyclopedia. 5 volumes or single ebook. ABC-CLIO. 2006.
  • Laffan, Thomas (1911). Tipperary Families : Being The Hearth Money Records for 1665–1667. James Duffy & Co.
  • MacLysaght, Edward, Irish Families: Their Names, Arms and Origins. Irish Academic Press. 4th edition, 1998.
  • Mac Niocaill, Gearóid, Ireland before the Vikings. Dublin: Gill and Macmillan. 1972.
  • Ó Corráin, Donnchadh, Ireland before the Normans. Dublin: Gill and Macmillan. 1972.
  • O'Donovan, John (ed. and tr.), Annála Ríoghachta Éireann. Annals of the Kingdom of Ireland by the Four Masters, from the Earliest Period to the Year 1616. 7 vols. Royal Irish Academy. Dublin. 1848–51. 2nd edition, 1856.
  • O'Hart, John, Irish Pedigrees; or the Origin and Stem of the Irish Nation 5th edition, 1892.
  • O'Keeffe, Eugene (ed. and tr.), Eoganacht Genealogies from the Book of Munster. Cork. 1703. (available here)
  • O'Rahilly, Thomas F., Early Irish History and Mythology. Dublin Institute for Advanced Studies. 1946.
  • Sullivan, Gary (2007). History of the O'Sullivan Clan: The Royal Blood of Gaelic Ireland. Gold Stag Communications, Inc. ISBN 978-0-6151-8013-7.

External links[edit]