do they have any successors in foreign nations?
Yes, in Scotland.
Anradhán kindred of Scotland/Scottish and Irish Clans related to Uí Neill Dynasty
Several Scottish families may descend from an O'Neill dynast named Anradhán. According to "Leabhar Chlainne Suibhne", Anradhán, son of Aodh Athlamháin, quarrelled with his elder brother, Domhnall, ancestor of the O'Neills, and left Ireland for Scotland.
the wolf and the lion game of thrones episode Fifth episode can you mention any characters from this episode? Lord Eddard Stark, Tyrion Lannister, Catelyn Stark can you mention any actor from this episode? Finn Jones, Kate Dickie, Lino Facioli, Brendan McCormack were some of them. where was the episode shot? The Paint Hall studio, Shane's Castle, Fort St Angelo (Maltese town of Vittoriosa). the castle that you just mentioned, is it a real castle? Yes, it is a ruined castle near Randalstown in County Antrim, Northern Ireland. when was it built? 1345 by whom? A member of the Clandeboy O'Neill dynasty. has it served as the filming location for any other works? UNANSWERABLE what are the origins of the dynasty that you just mentioned? Irish Gaelic origin were they rulers? Yes, they were Kings of Cenél nEógain.
Yes, France and Portugal. Yes, in France, Spain and Portugal Yes, the current head of the Clanaboy O'Neill dynasty, a descendant of João, is Portuguese nobleman Hugo Ricciardi O'Neill, the son of Jorge Maria O'Neill.
O'Neill dynasty O'Neill dynasty O'Neill dynasty
O'Neill Descendants in France, Spain, and Portugal O'Neill Descendants in France, Spain, and Portugal O'Neill Descendants in France, Spain, and Portugal

His son Conn (Constantine) O'Neill was an officer who spent his life in exile in France and married to Cecilia O'Hanlon. Their eldest son, João O'Neill (Shane O'Neill), was born in Richhill Village in the parish of Kilmore, Tyrone, and died in Santos o Velho, Lisbon, on 21 January 1788. He left France with his brothers and established their noble line permanently under in the Kingdom of Portugal. He was the titular head of the Clanaboy O'Neill dynasty, whose family have been in Portugal ever since. The current head of the Clanaboy O'Neill dynasty, a descendant of João, is Portuguese nobleman Hugo Ricciardi O'Neill, the son of Jorge Maria O'Neill; the family has been remarkable in the modern history of Portugal. 
His son Conn (Constantine) O'Neill was an officer who spent his life in exile in France  The current head of the Clanaboy O'Neill dynasty, a descendant of João, is Portuguese nobleman Hugo Ricciardi O'Neill, the son of Jorge Maria O'Neill; the family has been remarkable in the modern history of Portugal.
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O'Neill dynasty [SEP] Anradhán kindred of Scotland/Scottish and Irish Clans related to Uí Neill Dynasty
Several Scottish families may descend from an O'Neill dynast named Anradhán. According to "Leabhar Chlainne Suibhne", Anradhán, son of Aodh Athlamháin, quarrelled with his elder brother, Domhnall, ancestor of the O'Neills, and left Ireland for Scotland. This source states that Anradhán won extensive lands by conquest, and married the daughter of the King of Scots. Anradhán, who does not appear in contemporary sources, was apparently an 11th-century dynast, son of Aodh Athlamháin, King of Aileach (died 1033). Although "Leabhar Chlainne Suibhne" states that Anradhán gained his lands through conflict, it is possible that he secured these lands in Argyll through marriage to their heiress.