Hannacrois Creek is a 20.9-mile-long (33.6 km) tributary to the Hudson River in the U.S. state of New York. From its source in Westerlo it flows through Dunbar Hollows and over Dickinson Falls to the Alcove Reservoir. It then passes through Coeymans Hollow and just into Greene County to its mouth at the Hudson River in Coeymans, New York.