The Willard Brook Quarry is a prehistoric stone quarry site in a remote portion of Piscataquis County, Maine. The quarry site is located on one of a series of outcrops near Munsungan Lake in north-central Maine, all of which have yielded stone tools found at prehistoric sites throughout northern New England. The area is known to have been frequented by Native Americans, with an extensive array of habitation sites located in the area between Munsungan and Chase Lake. The Willard Brook quarry site provides evidence that Native Americans engaged in quarrying and mining operations to recover stone suitable for conversion to tools.