Colliford Lake is a reservoir on Bodmin Moor, Cornwall, England, United Kingdom. Covering more than 900 acres (3.6 km), it is the largest lake in Cornwall. It is situated south of the A30 trunk road near the village of Bolventor, the approximate centre of the lake being at OS grid reference SX179730. Dozmary Pool outfalls into the lake and the lake's own outfall forms one of the tributaries of the River Fowey.

The northernmost point of the lake is approximately three-quarters of a mile (1 km) south of Bolventor at OS grid reference SX184756 and the headbank at the southernmost point is approximately three miles (5 km) south of Bolventor at OS grid reference SX177709.

Leisure facilities on the site include angling and a 50-acre (200,000 m) adventure and nature park, Colliford Lake Park, which features trails and footpaths, play areas, wetlands, picnic areas and a cafe.

Colliford Lake is managed by the South West Lakes Trust, an environmental and recreational charity which manages fifty inland water sites in Cornwall, Devon, and Somerset.

• List of reservoirs and dams in the United Kingdom