Ó Dubhagáinn

Ó Dubhagáinn was the name of a bardic family from Baile Uí Dhubhagáin, in Uí Maine, (now Ballyduggan, Loughrea, County Galway). The family were not related to similarly named family of Dugan of Fermoy, County Cork.

The name is now generally rendered as Dugan.

...
Wikipedia