I happenened on this site while looking for a Carroll. I thought you would like to see. This is only a small portion as I'm not sure if it's copyrighted. But you can go to the source. The Malone Family Directory. MJhttp://www.malonedirectory.com/Kennedy.html
"The eponymous ancestor of the O'Kennedys was Kennedy, nephew of Brian Boru, or Cinneide in Irish, the resultant surname being O Cinneide (Brian Boru's father was Cinneide). They are thus a Dalcassian sept, and at first their territory was around Glenomra near Killaloe, and their occupation is perpetuated by the name of the civil parish comprising that area, viz. Killokennedy, but pressure from the powerful O'Briens and MacNamaras caused them to cross the Shannon and settle in Upper and lower Ormond. There they soon increased in power and importance, and from the eleventh to the sixteenth century they were lords of Ormond. The sept divided into three branches, the chiefs of which were distinguished by the epithets Don (brown), Fionn (fair) and Rua (red). The Four Masters record the martial exploits of many of these chiefs. According to Keating, St. Ruadhan of Lorrha was the special protector of the O'Kennedys of Ormond. A branch of the sept emigrated to Antrim about the year 1600, and the name is found in that county now, though, no doubt, some of the Ulster Kennedys are of Scottish origin, for Kennedy is also a Scots name. Kennedy, indeed, is one the commonest names in Ireland, being widely distributed over all the provinces, with a preponderance in Co. Tipperary: it is placed sixteenth in the statistical list of Irish surnames with an estimated present day population of some eighteen thousand persons. Unlike most Irish surnames Kennedy has few synonyms in English: one, however, still found in Co. Leitrim is interesting, viz. Minnagh, I.e. Muimhneach - or the Munster man (cf. Donlevy - Ultagh). Kennedy became Quenedy in Spanish, for, like all the great Irish families, many of the sept found their way to the continent. Matthew Kennedy (1652-1735), who went to France after the capitulation of Limerick in 1691, was a notable literary figure in Paris: he was remarkable for his life-long enthusiasm for the Irish language. At home the O'Kennedys, though remaining Catholic, were not entirely submerged as a result of the successive conquests and confiscations of the seventeenth century: an Order of the Lord Lieutenant, dated 30th March, 1705, granting permission to a few selected papists to carry arms, including eight gentlemen of Co. Tipperary, and among them is John Kennedy of Polnorman. Go to this site to read much more."