The Irish 'O'-prefix surnames (O'Brien, O'Connor, O'Donnell, O'Neill) all use
奥 as the standard '-O' character, then transliterate the rest. So
奥康纳 = O'Connor,
奥布莱恩 = O'Brien,
奥唐纳 = O'Donnell. The Irish 'O' originally meant 'descendant of', so an 'O'Donnell' is 'descendant of Donnell (Domhnall, world-ruler)'.