East Flattop Mountain is an 8,361-foot peak in the Lewis Range of Glacier National Park, Montana, standing north of Saint Mary Lake. Its broad profile makes it a prominent feature on the park’s eastern side, where it is readily visible from the eastern entrance to the Going-to-the-Sun Road and from the village of St. Mary. Rising above the lake near one of the park’s main approach routes, it has long served as a familiar landmark in the Saint Mary area.