'OBrien01'Index links to: Lead / Letter
Families covered: O'Brien Kings of Ireland, Munster and Thomond
Note. Ireland was divided into five kingdoms: Ulster, Munster, Leinster, Connaught and Meath. Thomond was North Munster.

Brian Boru, King of Ireland (b c926, d 23.04.1014)§A
partner(s) unknown
1. Murchad O'Brien (d 1014)
  A. Toirrdelbach O'Brien
2. Teige (Terence) O'Brien (d 1023)
  A. Toirrdelbach (Turlough) O'Brien, King of Munster and Ireland (d 14.07.1086)
  i. Muirchertach II O'Brien, King of Munster and Ireland (d 13.03.1119)
  a. Blathmin O'Brien (b 1095)
  m. (1100) Sigurd I Magnusson, King of Norway (b c1089, d 26.03.1130)
  b. Mathgamain O'Brien, Prince of Corcobaskin (d 1129) ancestor of the McMahons
  c. Domnall O'Brian, King of Dublin (d 1135)
  d. Lafrocath O'Brien JY
  Not recorded by RoyalData but 'The Origin and History of the Montgomeries' by BG De Montgomery (1948) identifies Arnulf's wife as "Princess Lafracoth, daughter of Murtagh O'Brien, King of Munster".
  m. (1101) Arnulf de Montgomery, lord of Pembroke 'Cimbricus' (a 1090, 1160) JY
  ii. Diarmait (Dermot) O'Brien, King of Munster (d 1118)
a. Toirrdelbach (Turlough) O'Brien, King of Thomond (d 1167)
  (1) Constantin O'Brien, Bishop of Killaloe (d 1194)
  (2) Muirchertach O'Brien, King of Desmond (d 1168)
  (3) Donnell More O'Brien, King of Munster (d 1194)
  m. Urlachan (dau of Diarmait MacMurchada (Dermot MacMurrough), King of Leinster) @@ below
  (A) Muirchertach Finn O'Brien, King of Thomond (d 1241)
  (B) Conchobar Ruad O'Brien, King of Thomond (d 1203)
  (C) Donnchad Cairprech (Cairbreach) O'Brien, King of Thomond (d 1242)
  (i) Toirdelbach O'Brien (d 1243)
  (ii) Muirchertach O'Brien (d 1241)
  (iii) Conchobar (Conor) Na Suidaine macDonnchada O'Brien, King of Thomond (d 22.05.1258)
(iv) Slaney O'Brien (Abbess of Killone Abbey)
  (D) Domnal Connachtach O'Brien
  (E) Muirchertach Dall O'Brien
  Not recorded by RoyalData but www.lawrencetown.com/longago.htm reports that, in or about 1193, three daughters of Donnell O'Brien (then King of Thomond) respectively married William De Burgh, the head of the O'Kelly clan, and Cathal Crovderg (brother of Rory O'Connor). The connection was first found in another source, and the name of Mor recorded, but the identity of that source was unfortunately not recorded ! That source identified Mor as (apparently married) mother of William's eldest son Richard, who was born about 1191, so it is assumed that Mor married William in about 1190.
  (F) Mor O'Brien Y
  m. (c1190) William de Burgh, Lord of Connaught (d 1205) Y
  (G) Duncola or Dubh Chabla O'Brien
  m. Domhnall (Daniel) Mor O'Ceallagh, Chief of Hy-Many (d c1224)
  (H) daughter named 'Mor' by O'Conor records
  m. Cathal Crovderg (brother of Rory O'Connor)
  (4) Brian O'Brien (d 1168)
  b. Conchobar O'Brien, King of Thomond (d 1142)
  (1) Muirchertach O'Brien (d 1151)
  (A) Conchabar "Slaper Salach" O'Brien (d 1168)
  c. Tadg Glae O'Brien, King of Desmond (d c1154)
  (1) Diarmait O'Brien
  (A) Connor O'Brien
d. Donnachad O'Brien, Bishop of Kilaloe (d 1164)
  iii. Tadg O'Brien, King of Munster (d 1108)
  a. Domnall O'Brien, King of the Isles (d 1115)
  b. Amlaib O'Brien (d 1096)
  iv. Donnchad O'Brien (d 1103)
3. Domnall Ban O'Brien (d 1052)
  A. Diarmait O'Brien (d 1051)
4. Slani O'Brien
  m. Sihtric 'Silkbeard', King of Dublin (d 1042)
m. Gormflaeth ingen Murchada MacFinn
5. Donnchad O'Brien, King of Munster (d 1064)
partner(s) unknown
  A. Deabforgail O'Brien (d 1080)
  m. Diarmait MacMail (Dermot MacMailnamo), King of Ireland (d 1072)
  i. Murchad, King of Leinster (d 1070)
  a. Donnchad, King of Leinster (d 1151)
  (1) Diarmait MacMurchada (Dermot MacMurrough), King of Leinster (d 1171)
  m. Mor O'Toole (dau/sister of Murtoug O'Toole of Omurethy)
  (A) Donall Kavanagh (Caomhanagh) ancestor of Kavanagh families
(B) Urlachan Y
  m. Donnell More O'Brien, King of Thomond (d 1194) @@ above Y
  (C) Aoife or Eve (d 1177) HJRY
  m. (26.07.1171) Richard 'Strongbow' de Clare, 2nd Earl of Pembroke (b c1125, d 20.04.1176) HJRY
  B. Murchad O'Brien, King of Munster (d 1068)
  i. Brian O'Brien, King of Munster (d 1118)
  ii. Moy O'Brien
  m. Murchad O'Neill (dau of Domnaill O'Neill, King of Mide)
  C. Lorcan O'Brien (d 1078)
  i. Conchbar O'Brien, King of Tulach (d 1078)
  ii. Cennetig O'Brien, King of Tulach (d 1084)
  p/m. Driella (dau of Godwin, Earl of Wessex and Kent)
  D. Donald Bane O'Brien

Main source(s):
(1) 'RoyalData'. The names given in that site are sometimes simplified above. Apologies are offered should that simplification (from what may be the technically correct old Irish method) be wrong.
(2) "The Royal Line of Succession", edited by Patrick Montague-Smith, Pitkin Guides Limited, 1996 reprint, ISBN 0-85372-404-0
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