Cétadach was the 31st Abbot of Clonmacnoise. He died in 848.
Cétadach succeeded Rónán, who resigned in 823 but only died in 844. Events which occurred during his abbacy included:
The Annals of the Four Masters state of him:
Cetadach, Abbot of Cluain Mic Nois, died. He was of the tribe of Ui Cormaic Maenmhaighe (Máenmaige). It was in lamentation of him this quatrain was composed:All have heard it/both uncommon and common/That an abbot at Cluain like Cedadach/will never again be seen.