Reilly

The Reillys, Gaelic Ó Raghallaigh or descendants of Raghallach, were the ruling dynasty of East Breifne, the Gaelic kingdom that became County Cavan. They were close kin of the O'Rourkes, once their overlords. Backed by Connacht, the Reillys eclipsed them in the 1230s, and their long war ended in 1256 with the partition of Breifne between the two families.

Their kings were chosen by tanistry and inaugurated on Shantemon Hill above Cavan town. East Breifne minted its own silver coinage, called Reillys, which Dublin outlawed in 1447 and 1456. The chief Maolmordha O'Reilly attended the English crown's parliament in 1541 under surrender and regrant.

In 1579 the kingdom was shired as Cavan. The Reillys joined the rebels in the Nine Years' War, and after defeat in 1603 and attainders by 1607 the lordship was swallowed by the Plantation of Ulster.