Mary Countess of Bantry (1805-1857), descendant of Brian Boru. 01 Sunday Mar 2015 Posted by durrushistory in Uncategorized ≈ Leave a comment Mary Countess of Bantry (1805-1857), descendant of Brian Boru. From St.Brendan’s Church Bantry. The O’Briens of Thomond are the descendants of Brian Boru. Share this: Click to share on X (Opens in new window) X More Click to share on Facebook (Opens in new window) Facebook Like Loading...