genealogies of the families
(O)CONNELLAN, Conlan, Conlon. Conlan, Conlon and Connellan are all synonyms (readers outside Ireland who might tend to stress the second syllable - ell - of Connellan may need to be told that in fact it is barely audible, Connellan and Conlan being pronounced almost alike). Several different Irish surnames have been so anglicized. The principal septs so called in English are O Conalláin of Roscommon and Galway and O Coinghiolláin of Co. Sligo: their present day representatives are chiefly found in north Connacht - in Counties Mayo and Sligo. The name is also fairly numerous in Co. Meath and the midlands, where however they are also called Quinlan - ÓCoindealbháin in Irish: they descend from an important sept seated near Trim which traces back to Laoghaire, King of Ireland in the time of St. Patrick, but was dispossessed at the Anglo-Irish invasion. In Munster ÓCoindealbháin, usually anglicized Quinlevan, is sometimes called Conlon. (For Quinlan and Quinlevan see below).
(In the seventeenth century the name was very numerous and widespread. In Petty's census (1659) it appears, under seven different spellings, as one of the commoner names in Counties Roscommon, Sligo, Longford, Westmeath, Offaly, Kildare and Louth.
The spelling Connellan is infrequent in modern times, compared with Conlan and Conlon, only about ten per cent. using that form; but so far as distinguished men of the name are concerned Connellans are outstanding. "The Book of the O'Connellans", a mediaeval work in Irish, deals with Tirconnell genealogies. Abraham O'Connellan was Archbishop of Armagh from 1247 to 1260 and Thomas O'Connellan, Bishop of Achonry from 1492 to 1508. Thomas O'Connellan (c. 1620-1685), was a composer of Irish airs and noted harper, as was his brother Laurence, who was well known in Scotland as a wandering harper after 1700. Owen Connellan (1800-1869), another north Connacht man, was an eminent Gaelic scholar; and Joseph Connellan, Nationalist Six-County M.P. was one of the active pioneers of Sinn Fein and the Gaelic Athletic Association in Ulster.
The well known war-cry "Conlan abu" was not connected with any of these septs: it was used by the O'Mores of Leix.
Source:Irish Families by Edward MacLysaght MA, D Litt, MRIA - Irish Academic Press 1991