Cynddelw Brydydd Mawr ap Trahaearn (, 11551195) was the court poet of Owain Cyfeiliog, Madog ap Maredudd, Owain Gwynedd, Hywel ab Owain Gwynedd, Rhys ap Gruffudd, and Llywelyn ab Iorwerth. He was the most prominent Welsh poet of the 12th century, noted for his archaising and bombastic style and proud conservatism. He was also likely the teacher of Prydydd y Moch, one of the most important Welsh poets of the thirteenth century.
Cynddelw's date of birth is unknown, but a pair of lines in his (death-bed poem) may refer to the name of his home parish:
As Cynddelw began his career in Powys, this suggests he was born in Llanfihangel-yng-Ngwynfa, then a part of the cantref of Mechain in the Kingdom of Powys.