John Mág Tighearnán, the First, (anglicised John McKiernan) was chief of the McKiernan Clan of Tullyhunco, County Cavan until his death in 1499.
[1] On the death of the previous chief, John took the chieftaincy and resided in the castle of Croaghan of the Cups (Irish- Cruachan O'Cúbhrán), now in the townland of Coolnashinny, beside the later town of Killeshandra.
In 1495 a relative died.
The Annals of Ulster for 1495 state- Mag Tighernain ‘Ichtarach’, namely, Gormgal, son of Brian Mag Tigernain, died John died in 1499.
The Annals of Ulster for 1499 state- Mag Tighernain of Tellach-Dunchadha, namely, John Mag Tighernain, died this year.