Eagley Brook (also known during the formative part of its course as Belmont Brook) is a small river of Lancashire and Greater Manchester in England. Rising at the confluence of several smaller streams at Old Man's Hill in the West Pennine Moors, the brook almost immediately feeds Belmont Reservoir, after which it moves south and south east, passing the village of Belmont and collecting several tributaries and traversing the Longworth Clough, emerging close to Egerton.