Dúnchad (d. 728), son of Murchad and overking of Leinster, was a member of the Uí Dúnlainge dynasty. Although his father Murchad (qv) son of Bran Mút had died as overking of Leinster in 727, the name of Dúnchad's mother is unrecorded. The genealogies indicate that he had at least three brothers or half-brothers, Fáelán (qv), Muiredach and Bran Becc.
Dúnchad first came to prominence in 722, when he supported his father at the battle of Almu (Hill of Allen, Co. Kildare) against the Cenél nÉogain king of Tara, Fergal (qv) son of Máel-dúin. A tradition recorded in the Fragmentary Annals (§178) ascribes the slaying of Fergal to Dúnchad. By this time, Dúnchad was already married to Tualaith (§207), daughter of the powerful Munster overking Cathal (qv) son of Finguine, who envisaged a role for himself as kingmaker in Leinster. In the mid 720s Dúnchad was defeated by the then king of Tara, Cináed Cáech (qv) son of Írgalach (qv), who was making an incursion into Leinster. Nonetheless, Dúnchad managed to assert Uí Dúnlainge authority over the Uí Chennselaig of south Leinster, defeating their king Laidcnén (§§181, 183) near Mullaghmast.
On the death of his father in 727, Dúnchad succeeded to the overkingship of Leinster. His reign, however, was destined to be short, as the Leinster king-list attests. Within a year, he was defeated and slain at Dún Ailinne (Knockaulin, Co. Kildare) by his brother Fáelán, who took the kingship and married his widow Tualaith, apparently against her father's wishes. Dúnchad's descendants became known as Uí Dúnchada, a distinct lineage within Uí Dúnlainge which created its own regional kingship centred on Liamain (Newcastle Lyons) on the Kildare–Dublin boundary. His son Cellach (qv) (d. 776) and his grandson Fínshnechtae Cetharderc (qv) later reigned as overkings of Leinster.