Risdeard O'Reilly

Risdeard O'Reilly (Risderd Ó Raghallaigh) was king of East Breifne, the O'Reilly kingdom in what is now County Cavan, from about 1328 until his death around 1349. He was the second son of Giolla Iosa Ruaidh, who had established the O'Reilly seat at Cavan.

When Risdeard's elder brother Maelseachleann died in 1328, after briefly being counted as king, Risdeard took the kingship. His long reign brought decades of stable O'Reilly succession, and when he died his brother Cu Chonnacht succeeded him.