Katherine Van Alst, 1946
Eight-year-old Katherine Van Alst disappeared from Devil's Den State Park, near Arkansas' Ozark National Forest, where she and her family were camping. Van Alst apparently was playing with her brothers when she wandered off and got lost, and what makes her disappearance remarkable is that when she was found after six days wandering the woods, she was eerily calm.
University of Arkansas student Porter Chadwick was part of the search party that found Van Alst. He told The Pittsburgh Press that when he found her, she walked stoically out of a cave and just said, "Here I am." Many other hikers have gotten lost in that part of the Ozarks and not been as lucky as Van Alst. A grown woman was lost there for 17 days and died just 50 yards (46 meters) from the road [source: Vistaramic Journeys].
A fan of David Paulides' books has taken several 360 degree panoramic shots of a few locations where people have mysteriously vanished, and you can see the area where Van Alst went missing here. The person who compiled these panoramas suspects abduction. In the shot, you can see places where an attacker, whether human or animal, may have hidden in thick brush or behind rock outcroppings. If it was indeed an abductor, was it a someone or a something lurking in Devil's Den?