McDonnell

Origin & Meaning

Mac Domhnaill is one of the most ancient and widespread surnames in the Gaelic world — shared by families in Scotland (MacDonald), Ireland (McDonnell), and the broader Gaelic diaspora. In Ireland, the most historically significant branch was the McDonnells of Antrim, who emerged as a major power in Ulster from the 14th century onward.

Originally from the Scottish Isles — they were a cadet branch of the MacDonald Lords of the Isles — the Antrim McDonnells established themselves in the Glens of Antrim, marrying into the local Gaelic families and gradually building dominance over northeast Ulster. At their height, they controlled territory from the Antrim coast to Rathlin Island and maintained close connections with their Scottish relations in Kintyre and Islay.

The family's most celebrated figure is Sorley Boy McDonnell (c.1505–1590) — Somhairle Buidhe, "yellow-haired Charles" — who resisted the Tudor conquest of Ulster for decades. His fortress at Dunluce Castle, perched dramatically on the Antrim coast, remains one of Ireland's most spectacular medieval ruins and a symbol of the McDonnell era.

History & Notable Bearers

Sorley Boy McDonnell's resistance to Queen Elizabeth I made him one of the most famous Gaelic chiefs of the 16th century. The massacre at Rathlin Island in 1575, when an English force killed hundreds of McDonnell women and children sheltering there, was one of the most notorious acts of the Ulster wars.

The McDonnells survived as Earls of Antrim into the 17th and 18th centuries. Randal MacDonnell, 1st Earl of Antrim (1570–1636), navigated the Jacobean settlement with skill. In modern Ireland, McDonnell/McDonald/MacDonnell families are found throughout Ulster and in significant numbers in the Irish-American diaspora, particularly in New York and New Jersey.

The McDonnell Diaspora

The McDonnell diaspora from Antrim and Ulster spread primarily to Scotland (where the shared Mac Domhnaill heritage blurred the boundary between Irish and Scottish identity), and to the United States, Canada, and Australia from the 19th century onward.

In America, Ulster McDonnell families settled in the Presbyterian communities of Pennsylvania and Virginia, and in the Catholic Irish communities of New York and Boston. The Scots-Irish McDonnell/McDonald families who came via Scotland to America in the 18th century are a related but distinct group. In Canada, Ontario and Prince Edward Island received significant Antrim emigration.

Genealogy Research

Antrim records

County Antrim records are held at PRONI (Public Record Office of Northern Ireland) in Belfast. Griffith's Valuation and Tithe Applotment Books show McDonnell families concentrated in the Glens of Antrim and across the county.

PRONI — Belfast

The Public Record Office of Northern Ireland holds extensive Presbyterian and Church of Ireland registers for Antrim, as well as Catholic registers for the Diocese of Down and Connor which covers County Antrim.

Dunluce Castle records

The McDonnell family papers, some of which relate to the Earls of Antrim, are held at PRONI and are a significant resource for researchers with direct McDonnell-of-Antrim lineage.