Milesius

In Irish mythology Milesius (or Mil Espaine, as he is most commonly named) was a descendant of Bregon, who is considered to have been the ancestor of the "first human rulers" of Ireland, thought to be the Celts; according to the legend, the pre-Celtic dwellers of Ireland (the Fomorians and the Tuatha De Danaan) were not humans. These "first human settlers" were known as the Milesians or Sons of Mil Espaine (it is thought by some authors that "Mil Espaine" means "Mil from Spain").

Milesius was a relative of Ith, who was the leader of a previous invasion to Ireland, but got killed by the Tuatha De Danaan; when Ith's corpse was taken back to Spain and he knew what had happened, Milesius prepared another invasion for retaliation; he could not arrive to Ireland but his sons, the Milesians, could, and they began the conquest of the country, on which succeeded.