The River Marron is a tributary of the River Derwent in Cumbria. The Marron is formed by the confluence of Colliergate Beck and Scallow Beck, near the village of Asby. The river flows north past Ullock, Branthwaite, Little Clifton and Bridgefoot. The Marron joins the River Derwent, about ½ mile north of Bridgefoot. The Marron has a catchment area of 53.6 km2 and is 20.8 km long.