Diarmaid mac Madudan was Chief of Síol Anmchadha from 1032–1069.
Described as a rod who ruled each road, Diarmaid was the son of Madudan mac Gadhra Mór. He led the Madden clan in a plundering raid on Clonmacnoise in 1050. However, he became blind in old age and was killed by his nephew, Madudan, and succeeded by his son, Madudan Reamhar Ua Madadhan.