Donnchad Donn
| Donnchad Donn | |
|---|---|
| High King of Ireland | |
| Reign | 919–944 | 
| Predecessor | Niall Glúndub | 
| Successor | Congalach Cnogba | 
| King of Mide | |
| Reign | 919–944 | 
| Predecessor | Conchobar mac Flainn | 
| Successor | Oengus mac Donnchada | 
| Died | 944 | 
| Spouse | 
 | 
| Issue | 
 | 
| House | Clann Cholmáin | 
| Father | High King Flann Sinna | 
| Mother | Gormlaith ingen Flann mac Conaing | 
Donnchad Donn mac Flainn (Duncan of the Brown Hair, son of Flann) (died 944) was High King of Ireland and King of Mide. He belonged to Clann Cholmáin, a branch of the southern Uí Néill.