  Black Irish refer to the Irish with Spanish blood in them.  After the English defeat of the Spanish Armada, some of the ships sailed around the top of England, and crashed into Ireland, and of course never left.  Their children were the original 'Black Irish.  That is just an old wive's tale. For the amount of Black Irish people there are today there would've had to been one helluva lot of Spaniards crash landing in Ireland and not all Spaniards are dark complected anyways.    The real reason for all of the so-called Black Irish (dark complected Irish that look Mediterranean) is because the original, very ancient inhabitants of Ireland were a darker complected, Mediterranean type people that sailed up to Ireland from Iberia. This has all been pretty well proven beyond much of a doubt by modern genetics testing and archaeological evidence. There is also some evidence to suggest that there may have been a small Phoenician presence in parts of Ireland, Scotland and Wales in ancient times as well.