Llwynda-Ddu Camp, also known as Llwynda-Ddu Hillfort, is a small Iron Age earthwork in Pentyrch, Cardiff in South Wales. The site is a scheduled monument, described as a prehistoric, defensive hillfort.
The plan of the camp is egg-shaped and lies at the western end of a small hill at a height of approximately . The ground falls away sharply on all sides except the eastern end. The entrance is at the smaller south-western end.
The camp probably comprised two ramparts with ditches but much of the outer ring has been destroyed. The entrance is a straight causeway which interrupts the inner and outer rings. The height of the bank is approximately higher than the ditch bottom. The inner area measures by giving an area of .
The site has been cultivated, with a modern dwelling nearby. It is suggested that the camp belonged to the Silures.