The following lineage family trees of different branches of the Clan are based on those contained in the book "The O'Donnells of Tyrconnell - A Hidden Legacy" (Washington DC, 2018/2019) and other sources. The first, a parchment style one, is of "The Principal Branches of O'Donnell Kings of Tyrconnell" from the Office of the Chief Herald of Ireland, and was prepared in the 1940s. It is erroneous in omitting entirely the first family of its "no.17" - Sir Hugh O'Donnell (actually the 23rd Ua Domhnaill), and in other errors. That is largely corrected in the succeeding charts. The next eight are also taken from that book. The next six thereafter are taken from the earlier book edited by the late Vincent O'Donnell "The O'Donnells of Tyrconnell - a concise history of the O'Donnell Clan", who based those charts mainly on the work of the late Rupert O Cochlainn, O'Donnell Clan genealogist. They include summary family trees of the O'Donnells of Newport, Castlebar, Larkfield, Austria, Spain and Glassagh. A further two present additional material on O'Donnells in West Kerry, based on their lore and local researchers.
NB: these charts are NOT exhaustive, nor necessarily correct in all detail, and may be replaced once better material emerges. Other lineages also exist. Please regard this material, and indeed this website as a "work-in-progress"
Genealogically certified as of direct patrilineal descent from the last family to rule as the undisputed dynasty of Kings, Princes, and Earls of Tyrconnell, the O'Donnells of Ardfert as also endorsed by several historians including kinsfolk, are directly descended from Sir Hugh Dubh MacManus O'Donnell, 23rd Ua Domhnaill, Lord and King of Tyrconnell, of a cadet line, through his eldest heir, Sir Donal O'Donnell, who served as Seneschal of Tyrconnell and Sheriff of Donegal until assassinated at the Battle of Derrylaghan, on the Feast of the Holy Cross, 14 September 1590. His son, Donal Oge O'Donnell, deployed briefly to Lixnaw, Ballykealy and Ardfert by his uncle Red Hugh O'Donnell II, departed on the Flight of the Earls in 1607, but left a family in Ardfert, some of whom later became the Jacobite O'Donnell Counts in France, now extinct. The eldest of the surviving Ardfert line is also related through a maternal line as second cousin thrice removed of the late Cardinal O'Donnell.
Find many more elements on this webpage, with "blue button" links to much else
http://www.fmodonnell.org/clan.html