O’Kellies, the, of the tribe of Hy-Maine, much scattered, but in this work chiefly between Tuam and Roscommon, [69], [75], [172], [334], [374]
O’Kelly, Hugh, [266]
O’Kennedy, of Ormonde in Tipperary, [120], [224], [227], [242], [266]
Olaf Cuaran, [21], [24], [25], [32]
— Sitricson, [29]
— Trygvesson, [32]
Oldcastle, Sir John, [388]
Olderfleet (Larne), [351]
Olfin, [18]
Olioll Olum, [22]