The Oxford Dictionary of National Biography states that Richard de Burgh (b. in or after 1259, d. 1326) was the second earl of Ulster, called the Red Earl, a magnate, and the lord of Connacht, and that he was [1]
… the eldest son and heir of Walter de Burgh, earl of Ulster (d. 1271), and of Avelina, daughter of John fitz Geoffrey, justiciar of Ireland (1245–56). …
He was granted seisin of his inheritance on 5 January 1281 … He married, before 27 February 1281, Margaret (d. 1304), said to have been the daughter of John de Burgh and a great-granddaughter of Hubert de Burgh, earl of Kent; in 1283 they were granted Ratoath, Meath, the former de Burgh property in Owney, Limerick, and the dower lands in Ulster of Hugh de Lacy's widow, by Queen Eleanor, who described Richard de Burgh as her cousin. …
De Burgh's wife died in 1304, as did his eldest son, William, without children (another son, Thomas, died in 1316). The earl's second son, John, now heir, married Elizabeth de Clare, daughter of Gilbert de Clare, earl of Gloucester (d. 1295); John and Elizabeth were thereby enfeoffed with manors in Ulster, Connacht, and Munster. His daughter Matilda married Elizabeth's brother, Gilbert de Clare, earl of Gloucester, who was killed at Bannockburn. She was originally betrothed to John, son of Peter of Bermingham, later earl of Louth, but Gloucester's envoys picked her as she was fairer than her sister Avelina, whom Bermingham married instead. Another daughter, Elizabeth, married the future Robert I of Scotland in 1302; Eleanor married Thomas Multon of Egremont; and, at Greencastle, Down, in 1312 a final reconciliation with the Geraldines was effected when de Burgh's daughter Joan married Thomas fitz John Fitzgerald, son of John fitz Thomas Fitzgerald, later earl of Kildare, and Catherine married Maurice fitz Thomas Fitzgerald, later earl of Desmond. …
Richard de Burgh went to parliament at Kilkenny in July 1326, described as infirm by the Dublin annalist … he retired to the priory of Athassel, Tipperary (founded by his great-grandfather), where, on 29 July, he died, and where he was buried. … The Irish annals call him 'the best of all the English of Ireland' (Annala Connacht, 261), and a bardic lament in Gaelic survives commemorating his death. Although he left at least one son, Edmund (d. 1338), he was succeeded by his grandson William de Burgh, then in his fourteenth year, later known as the Brown Earl.
[1] Seán Duffy, "Burgh, Richard de, second earl of Ulster [called the Red Earl] (b. in or after 1259, d. 1326)," Oxford Dictionary of National Biography (Oxford University Press, 2004, online edition), [Oxford_Dictionary_National_Biography], [OxfordDNB(UM)].