Gwerclas usually refers to a former castle and farmstead close to Cymmer in the parish of Llangar in the ancient cantref of Edeyrnion, Wales. It is now just an uninhabited upland area. The modest castle found at the site during the early Middle Ages is now completely ruinous. The ancient Barons of Cymmer yn Edeyrnion (known as the Hughes of Gwerclas) cite this place as their ancestral home. Prior to the resettling of the castle in 1186 by the ancestors of the Hughes family it was the power base of the mysterious Maer Du or "Black Mayors" of Edeyrnion.

• The Royal Tribes of Wales, Philip Yorke, London (1799),
• The Royal Families of England, Scotland and Wales, John Bernard Burke (1851), vol. 1, pedigree L11
• A Genealogical History of Abeyant, Forfeited, and Extinct Peerages of the British Empire, by Bernard Burke, John Burke, Published by Harrison, 1866, Oxford University

52°58′06″N 3°24′42″W / 52.9682°N 3.4118°W / 52.9682; -3.4118