Llyn Bedydd is a small lake in Wrexham County Borough, in northeastern Wales, near the border with England. It is 7 kilometres (4.3 miles) south west of Whitchurch. The lake and the surrounding woodland are designated as a Site of Special Scientific Interest.

Llyn Bedydd means the "lake of Beda", the identity of Beda is however not known.^[1]

Llyn Bedydd is 1 hectare (2.5 acres) in area^[2] and is surrounded by carr woodland of willow and alder which merges into drier deciduous woodland dominated by downy birch and sycamore higher up the slope.^[3]

The wet carr around the Llyn Bedydd is notable for purple small reed and alder buckthorn which are very rare in Clwyd; tufted sedge and bay willow which are uncommon in Clwyd; and the nationally scarce cowbane. The thin fringing strip of fen supports other interesting plants, especially sedges. The fen creates a tussocky species rich floating mat at the southern end of the lake while on the land in the southeastern corner of the SSSI there is a small area of fen pasture which grades into a bog. Llyn Beddyd is relatively shallow but it has steeply shelving banks which are shaded by the woodlands and these restrict the development of stands of emergent and marginal vegetation.^[3]

Llyn Bedydd is supports a rich invertebrate fauna, species recorded include the nationally scarce variable damselfly and the local red-eyed damselfly.^[3] Llyn Bedydd contains common bream, common rudd, common carp, European perch, tench and common roach. The fishing is run by Warners Fishing Club.^[2]

In 1877 a logboat was found in the Llyn Bedydd.^[4]

• List of Sites of Special Scientific Interest in Clwyd

52°56′50″N 2°47′10″W / 52.94722°N 2.78611°W / 52.94722; -2.78611