Llyn Cerrig Bach is a small lake located between Rhosneigr and Valley in the west of Anglesey, Wales.
Whilst it is not one of the largest lakes on the island (around 1.8 acres), its claim to fame is the group of over 150 Iron Age metal objects discovered there in 1942, apparently placed in the lake as votive offerings. These finds are considered to be one of the most important collections of La Tène style metalwork, or Early Celtic art discovered in the British Isles, and the most important in Wales.