Monarchical systems of government have existed in Ireland from ancient times. In most of Ireland, this continued until 1949, when it transitioned to being the Republic of Ireland. Northern Ireland, as part of the United Kingdom, remains under a monarchical system

• Máel Sechnaill mac Máele Ruanaid, 846–860
• Áed Findliath, 861–876
• Flann Sinna, 877–914
• Niall Glúndub, 915–917
• Donnchad Donn, 918–942
• Congalach Cnogba, 943–954
• Domnall ua Néill, 955–978
• Máel Sechnaill mac Domnaill, 979–1002 and 1014–1022
• Brian Boru, 1002–1014
• Donnchad mac Briain, died 1064
• Diarmait mac Máel na mBó, died 1072
• Toirdelbach Ua Briain, died 1086
• Muirchertach Ua Briain, died 1119
• Domnall Ua Lochlainn, died 1121
• Toirdelbach Ua Conchobair, c.1119-1156
• Muirchertach Mac Lochlainn, c.1156-1166
• Ruaidrí Ua Conchobair, 1166-1198
• Ruaidrí Ua Conchobair 1166 – 1198

• Aodh Méith mac Aodha O'Neill 1196–1230
• Brian O'Neill 1230– 1260
• Hugh Boy O'Neill 1260–1283
• Niall Culanach O'Neill 1283-1290
• Domhnall O'Neilln 1290-1325
• Brian O'Neill 1291–1295
• Henry O'Neill 1325–1345
• 1345-1498
• Domhnall Clarach O'Neill 1498–1509
• Art Oge O'Neill 1513–1519
• Conn Bacagh O'Neill 1519–1558
• Shane O'Neill 1559–1567
• Turlough Luineach O'Neill 1567–1593
• Hugh O'Neill 1593–1607. After that the British controlled it see:List of English monarchs