Butler Knob is a peak on the Jacks Mountain ridge in south central Pennsylvania in the United States. The "Knobs" summit is underlain with weather resistant quartzite of the Tuscarora Formation (Silurian Age). Butler Knob is accessible by a rough road, where there is a closed firetower on the summit. The firetower presently hold a weather station that gives current forecasts for the area (see link below).