Máel Dúin mac Máele Fithrich (died 681) was a King of Ailech and head of the Cenél nEógain branch of the northern Uí Néill.
[2] The annals record the destruction of Ailech in 676 by the high king Fínsnechta Fledach (died 695) of the southern Uí Néill who appears to have asserted his authority in the north.
In 677 he slew Dúnchad son of Ultán, king of Airgialla -of the Uí mac Carthainn, near Lough Foyle, Tirkeeran in modern County Londonderry- in Dún Forgo.
At the beginning of winter 681 he was defeated and slain at the Battle of Bla Sléibe (in modern County Londonderry) by the Ciannachta of Glenn Geimin and by Fland mac Máele Tuile (died 700) of the rival Cenél Feradaig.
[6] Máel Dúin mac Máele Fithrich is recorded as the ancestor of the Ó Dálaigh bardic family in the O'Clery Book of Genealogies.