Dubthach is a masculine personal name in early Ireland. It may refer to:
- Dubthach Dóeltenga, a character in the Ulster Cycle, ally of Fergus
- Dubthach maccu Lugair, legendary Irish poet and lawyer in the time of St Patrick
- Dubthach the First, Bishop of Armagh, Ireland from 497 to 513.
- Dubthach the Second, Bishop of Armagh, Ireland from 536 to 548