Hydrocolus is a genus of beetles in the family Dytiscidae, containing the following species:
Hydrocolus deflatus (Fall, 1923)Hydrocolus filiolus (Fall, 1923)Hydrocolus heggiensis Ciegler, 2001Hydrocolus oblitoides Roughley & Larson, 2000Hydrocolus oblitus (Aubé, 1838)Hydrocolus paugus (Fall, 1923)Hydrocolus persimilis (Crotch, 1873)Hydrocolus rubyae (Larson, 1975)Hydrocolus rufiplanulus (Fall, 1923)Hydrocolus rupinus Roughley & Larson, 2000Hydrocolus sahlbergi Nilsson, 2001Hydrocolus stagnalis (Gemminger & Harold, 1868)