Tudur ap Gruffudd (1365–1405), also known as Tudor de Glendore or Tudor Glendower, was the Lord of Gwyddelwern, a junior title of the princely house of Powys Fadog, and was the younger brother of Owain Glyndŵr, the Welsh rebel leader crowned Prince of Wales. His father was Gruffydd Fychan II, the hereditary Prince of Powys Fadog and previous Lord of Gwyddelwern. Along with his brother, Owain Glyndŵr, Tudur was a member of the royal House of Mathrafal.

Powys Fadog was the northern portion of the former princely realm of Powys. The princes of Powys Fadog would build their royal seat at Castell Dinas Brân, and their religious center at Valle Crucis Abbey. Some of its lordships included those of Maelor, Mochnant, Glyndyfrdwy, Yale, and Bromfield and Yale. Following the division of Powys, their cousin branch, the princes of Powys Wenwynwyn, would build Powis Castle.