Answer
Harlech Castle was captured by Owain Glyndŵr, a Welsh leader who led a revolt against English rule in the early 15th century. Glyndŵr's forces took control of the castle in 1404 and held it for several years, using it as a base for their operations. The castle was eventually recaptured by the English in 1409, but Glyndŵr's capture of Harlech Castle remains a significant event in Welsh history.