The Barkley Marathons is an annual ultramarathon in Frozen Head State Park near Wartburg, Tennessee, famed as one of the United States’ hardest trail races. Created from an idea by Gary “Lazarus Lake” Cantrell and Karl “Raw Dog” Henn, it began in 1986 and took its modern five-loop form in 1995. Its unmarked course, off-trail navigation, severe terrain, strict sixty-hour limit, hidden-book page checkpoints, and unusual entry rituals have made it notorious. Despite an official one-hundred-mile claim, the course is understood to be longer, and completions remain extremely rare, including notable milestones by Mark Williams in 1995 and Jasmin Paris in 2024.