O'Reilly

O'Reilly
*Ó Raghallaigh*
O'Reilly; Ó Raghallaigh
Parent house	Uí Briúin Bréifne
Country	Kingdom of Connacht
Founder	Ragheallach mac Cathalan
Final ruler	Maelmordha O'Reilly
Titles	King of East Bréifne; King of Muintir Maelmórdha; Conde de O'Reilly;
Dissolution	1602
Cadet branches	Brady; Vesey

O'Reilly (Irish: Ó Raghallaigh)^[1] is a common Irish surname. The O'Reillys were historically the kings of East Bréifne in what is today County Cavan. The clan were part of the Connachta's Uí Briúin Bréifne kindred and were closely related to the Ó Ruairc (O'Rourkes) of West Bréifne. O'Reilly is ranked tenth in the top twenty list of most common Irish surnames.^{[citation needed]} It is also the patronymic form of the Irish name Reilly (Irish: Raghallach).^[2] The name is commonly found throughout Ireland, with the greatest concentration of the surname found in County Cavan followed by Longford, Meath, Westmeath, Fermanagh and Monaghan, and the Province of Leinster.^{[citation needed]}

^ "Raghallach — Database of Irish-language Surnames". Gaois. Retrieved 26 December 2022.
^ "Ó Raghailligh - Irish Names and Surnames". www.libraryireland.com. Retrieved 26 December 2022.

[1] "Raghallach — Database of Irish-language Surnames". Gaois. Retrieved 26 December 2022.

[2] "Ó Raghailligh - Irish Names and Surnames". www.libraryireland.com. Retrieved 26 December 2022.

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