The panther attack scenes found in the fiction of Charles Brockden Brown (1771-1810), James Fenimore Cooper (1789-1851), and Harriet Prescott Spofford (1835-1921) portray these animals as literary monsters indicative of a developing American environmental anxiety. Drawing on a selection of recent critical studies dealing with both antebellum American fiction and ecocriticism, I suggest that these scenes reveal, especially through their depiction of panther attacks in what ecologists now refer to as anthropogenic ecotones (human-made environmental edges), the beginnings of an American cultural recognition of environmental degradation. Ultimately these panther attack scenes prefigure an American environmental ethic, revealing an instructive early stage in the evolving cultural perception of the human devastation to the natural world.