Background: There are some five thousand persons in Ireland to-day bearing the surname Henry - without O or Mac. The majority of these are Ulstermen formerly called O'Henry, the Irish form being H hInneirghe. the head of this sept was chief of Cullentra in Co. Tyrone whose territory at one time extended to the valley of Glenconkeine in Co. Derry.
Fitzhenry, sometimes abbreviated to Henry, is the name of a Norman family chiefly associated with Co. Wexford but having a branch in Connacht. The latter, becoming hibernicized like so many Norman families in Connacht, were in the sixteenth century records regarded as an Irish sept: they were tributary to the O'Flahertys of Moycullen and Ballynahinch and were called Mac Einri in Irish, which in due course was made MacHenry in English.