Cathal O'Conor was king of Connacht from 1280 to 1288.
Cathal O'Connor or Cathal O'Conor may also refer to:
Kings of Connacht Cathal mac Conchobar mac Taidg, king of Connacht, died 1010 Cathal Carragh Ua Conchobair, king of Connacht from 1189 to 1202 Cathal Crobhdearg Ua Conchobair, 12th/13th-century king of Connacht
Other Cathal Ó Conchobair, 14th-century Irish bishop Cathal O'Connor Faly, 16th-century Irish rebel, known as Don Carlos