Gilla Mo Dutu Úa Caiside (fl.
1147) was a Gaelic Irish poet.
Closely associated with Tighearnán Ua Ruairc, King of Bréifne, he was attached to the monastery of Daminis and possibly to the church of Ard Brecáin, being a cleric.
His two famous compositions are Éri óg inis na náem and the Banshenchas.
The Ó Caiside family later became – from the 14th century – prominent in Fermanagh, and many of them became hereditary doctors to the Maguire chieftains.