| Cynfyn Conbinus | |
| King of Ergyng | |
| Reign: | c. 585 – c. 615 |
| Predecessor: | Peibio Clafrog |
| Successor: | Gwrfoddw |
| Issue: | Gwrgan Fawr |
| Father: | Peibio Clafrog |
King Cynfyn (Latin: Conbinus; died c. 615) was the King of Ergyng, a kingdom of south-east Wales in the early medieval period. He was the son of Peibio Clafrog.
Little is known of Cynfyn ap Peibio apart from the evidence of later medieval genealogies. He appears a number of times in the Llandaff Charters, particularly in association with Bishop Aeddan and Bishop Elwystl.