Brennan surname meaning

Brennan is an anglicized Irish surname with more than one closely spelled patronymic source. Ó Branáin or Mac Branáin means descendant or son of Branán, a diminutive personal name traditionally associated with a raven. Ó Braonáin supplies another route based on Braonán, from braon, “drop,” and several unrelated Irish septs used the name. Brannan and Brannon are common spelling variants. The surname-level descendant-name structure is clear even though the older personal-name glosses differ, so parent’s name is high confidence. Different septs need not descend from one common Brennan ancestor.