The Hazel Brook, also known as the Hen, is a tributary of the River Trym in Bristol, England. It rises at Cribbs Causeway in South Gloucestershire. From there, its course takes it south, passing the western end of Filton Aerodrome on its left bank, through Brentry and Henbury before dropping through a steep limestone gorge in the Blaise Castle estate. It continues south through two lakes before joining the Trym at Coombe Dingle.