Anglicised variations: Kelly, Kelley, O’Kelly, Kealy, Keely, Keily, Kehelly, Kehilly, Coakley.

Kelly is the second most common surname in Ireland and originates from at least seven different and unrelated ancient clans or septs. These include O’Kelly septs [...]]]> Gaelic variations:
Ceallaigh, Ceallach, Ó Ceallaigh, Ó Caollaidhe, Ó Caollaighe, Ó Cadhla, Mac Caochlaoich: “war or contention”.

Anglicised variations:
Kelly, Kelley, O’Kelly, Kealy, Keely, Keily, Kehelly, Kehilly, Coakley.

Kelly is the second most common surname in Ireland and originates from at least seven different and unrelated ancient clans or septs. These include O’Kelly septs from Meath, Derry, Antrim, Laois, Sligo, Wicklow, Kilkenny, Tipperary, Galway and Roscommon, and the McKelly sept from East Connaught.

One of the major septs is the O’Kellys of Ui Maine, or Hy Many, a territory in East Galway and South Roscommon. O’Kelly derives from the Gaelic O Ceallaigh, meaning “descended from Ceallach.” Ceallach was the son of Finnachta, a chief of the Hy Many people around A.D. 874.

Here’s a list of various clan websites:

Kelly Clan Association – Muintir Uí Cheallaigh

Kelly Clan Association – Kelly Places and People

The Kelly Clan, County Armagh, Northern Ireland.

Kelly may also mean ‘bright-haired’ or ‘troublesome’ – you choose!