Marks Knob is a mountain in the Great Smoky Mountains, in the southeastern United States. It has an elevation of 6,169 feet (1,880 m), with 249 feet (76 m) of clean prominence. Its summit— located near the center of the Eastern Smokies amidst a dense stand of Southern Appalachian spruce-fir forest— is a popular bushwhacking destination and one of the most difficult-to-reach summits of the Southern Sixers.