The Barkley Marathons is an ultramarathon trail race held each year in Frozen Head State Park in Morgan County, Tennessee, United States.

The course, which varies from year to year, consists of five loops of the 20+ mile, off-trail course for a total of 100 miles (160 km). The race is limited to a 60-hour period from the start of the first loop, and takes place in March or early April of each year. The race is known for its extreme difficulty and many peculiarities.

The Barkley course was the brainchild of Gary "Lazarus Lake" Cantrell and Karl "Raw Dog" Henn. The idea for the race was inspired upon hearing about the 1977 escape of James Earl Ray, the assassin of Martin Luther King Jr., from nearby Brushy Mountain State Penitentiary. Ray covered only about 12 miles (19 km) after running 54.5 hours in the woods hiding from air searches during the day. Mocking Ray's low mileage, Cantrell said to himself, "I could do at least 100 miles". Thus, the Barkley Marathons was born. Cantrell named the race for his longtime neighbor and running companion, Barry Barkley. It was first run in 1986. Barkley died in 2019 at age 70.

For the early years, the Barkley course was approximately 50–55 miles (80–89 km), with about 25,000–27,000 feet (7,600–8,200 m) of climbing. In 1988 "Frozen" Ed Furtaw, from North Carolina, became the first to finish the original short version of the course with a time of 32:14. In 1989, the course was extended. The 55-mile (89 km) version was referred to as “the short one” and the 100-mile (160 km) version, “the long one.” In 1995, Mark Williams, of the United Kingdom, became the first participant to finish the full longer version of the Barkley Marathons with a time of 59:28:48.

The 2020 event was cancelled due to the COVID-19 pandemic.

In 2023, British runner Jasmin Paris became the fourth woman to complete the 3 loop 'Fun Run' twice and only the second to start the 4th loop. Sue Johnston previously started the fourth loop in 2001. Previous women to have completed the 3 loop 'Fun Run' are Suzi Thibeault (1991, 1994), Nancy Hamilton (1991, 1993), Sue Johnston (2000, 2001) and Beverley Anderson-Abbs (2012, 2013). They have all completed the 3 loop 'Fun Run' twice. In 2024, Paris became the first woman to complete all five loops within the time limit, finishing the event 99 seconds before the 60-hour cut-off.

The Barkley is limited to 40 runners and usually fills up quickly the day registration opens. Requirements and times to submit an entry application are a closely guarded secret with no details advertised publicly. Potential entrants must complete an essay on "Why I Should be Allowed to Run in the Barkley," pay a $1.60 application fee, and complete other requirements subject to change. If accepted, an entrant receives a "letter of condolence." Upon arriving, first-time Barkley runners, known as virgins, are required to bring a license plate from their state/country as part of the entrance fee. Previous racers are required to bring an additional "fee" which in the past has included things such as a white shirt, socks, or a flannel shirt, as a donation for being a non-finisher. These donations are apparently based on the current needs of Lazarus Lake at the time. Prior finishers of the marathon who return to run again must submit a pack of Camel cigarettes as part of the registration fee. Race bib number one is always given to the person deemed to be the least likely to finish one lap out of all who have applied; a "human sacrifice," as Cantrell calls it.

The course itself, which has changed distance, route, and elevation many times since its inaugural run, currently consists of an approximate 20-mile (32 km) unmarked loop with no aid stations except water at two points along the route. Runners are allowed to study and copy the course map prior to the race, but once the race is underway they must navigate by their own notes alone. The loop begins and ends at the yellow road gate where the runners' and supporters' parked cars stay. Runners of the 100-mile version run this loop five times, taking a counterclockwise direction for loops two and four, followed by each runner alternating direction on loop five, after the first-placed runner's choice. Depending on the start time of the first loop, either the second and fourth loops are run at night, or the first, third, and fifth loops are run at night. Runners who complete three circuits of the loop (60 miles) are said to have completed a "fun run".

With 54,200 feet (16,500 m) of accumulated vertical climb (and the same amount of descent), the 100-mile run is considered to be one of the most challenging ultramarathons held in the United States, if not the world. As of 2018, about 55% of the races had ended with no finishers.

The 100-mile and 60-mile distances are nominal. While a nominal distance of 20 miles, which only covers the horizontal distance, the actual length of the loop varies due to changes in the elevations on the course. Some say the loop is as long as 26 miles (42 km), yielding 130 miles (210 km) for the full race and 78 miles (126 km) for the "fun run." The race course is not consistent between years; Cantrell modifies it to ensure it remains "at the very horizon of human potential", making it more difficult each time someone finishes. Cantrell argues that most runners should fail to complete the race, as failure is essential to growth.

The Barkley starts any time from midnight to noon on race day, with one hour till race start signaled by blowing a conch. The race officially begins when the race director lights a cigarette.

In addition to running, competitors must find between 9 and 15 books along the course (the exact number varies each year) and remove the page corresponding to the runner's race number from each book as proof of completion. Because of this, competitors are only issued odd numbers. Competitors get a new race number, and thus a new page requirement, at the start of each lap.

The cut-off time for the 100-mile race is 60 hours overall, or an average of 12 hours per loop, and the cut-off for the 60-mile version of the race is 40 hours overall, which averages out to 13 hours and 20 minutes per loop. This also includes any rest/food time between loops. Once a competitor has started a loop (noted by the time they touch the famous yellow gate after collecting their bib) they are not allowed to receive any assistance, other than from fellow runners, until they have finished that loop. Out of more than 1,000 starts, the 100-mile race has been completed within the official 60-hour cut-off 26 times by 20 different runners, with one two-time finisher, one three-time finisher, and one four-time finisher. However, in 2006, nobody finished even the 60-mile "fun run" in under 60 hours. Prior to Jasmin Paris's finish in 2024, as well as her 2023 performance (getting to the 9th book on the 4th lap), the best women's achievement was Sue Johnston's 66 miles (106 km) in 2001. More than 30 competitors failed to reach the first book (two miles).

When a runner drops out of the race, a bugler plays "Taps" upon their return to the start/end point.

In 2017, Gary Robbins of North Vancouver, British Columbia, reached the finishing gate a mere six seconds after the 60-hour cut-off, almost becoming the 16th runner ever to complete the Barkley. However, he had taken a wrong turn in the final stages of the race, thus cutting two miles off the course; he would have been disqualified even if he had been faster. "The time, in that situation, is meaningless," Cantrell said of the six-second time overage.

In 2022, the race had its second earliest start in history, with the ceremonial cigarette being lit on March 8 at 6:54 AM local time. The only earlier date was the first event, 1986, when the race started on March 1.

As of the end of the 2024 event, the full, five-loop race has been completed within 60 hours a total of 26 times by 20 runners.

Official finishers of the Barkley Marathons

Year	Name	Time	Notes
1995	Mark Williams	59:28:48	First male finisher
2001	David Horton	58:21:00	New record
	Blake Wood	58:21:01
2003	Teddy Keizer	56:57:52	New record
2004	Mike Tilden	57:25:18
	Jim Nelson	57:28:25
2008	Brian Robinson	55:42:27	New record
2009	Andrew Thompson	57:37:19
2010	Jonathan Basham	59:18:44
2011	Brett Maune (1)	57:13:33
2012	Brett Maune (2)	52:03:08	Current record
	Jared Campbell (1)	56:00:16
	John Fegyveresi	59:41:21
2013	Nick Hollon	57:39:24
	Travis Wildeboer	58:41:45
2014	Jared Campbell (2)	57:53:20
2016	Jared Campbell (3)	59:32:30
2017	John Kelly (1)	59:30:53
2023	Aurélien Sanchez	58:23:12
	John Kelly (2)	58:42:23
	Karel Sabbe	59:53:33
2024	Ihor Verys	58:44:59
	John Kelly (3)	59:15:38
	Jared Campbell (4)	59:30:32
	Greig Hamilton	59:38:42
	Jasmin Paris	59:58:21	First female finisher

• Big's Backyard Ultra

Furtaw, Ed. (2010) Tales From Out There: The Barkley Marathons, The World's Toughest Trail Race, CreateSpace. ISBN 1-4505-4701-X

This article's use of external links may not follow Wikipedia's policies or guidelines. Please improve this article by removing excessive or inappropriate external links, and converting useful links where appropriate into footnote references. (March 2024) (Learn how and when to remove this message)

• Matt Mahoney's Barkley Marathons Site
• Top 10 Barkley Documentaries
• The Believer magazine article - "The Immortal Horizon"
• "Out There" at the Barkley: Portraits From the Edge of Endurance
• "Barkley 100" documentary short film by Brendan Young
• Interview with Nick Hollan after 2013 Barkley Marathons from Talk Ultra Podcast
• Interview with 3-time finisher Jared Campbell and Gary Robbins after 2015 Barkley Marathons from the Ginger Runner Live Podcast
• Interview with Guillaume Calmettes, Maggie Guterl, and Amelia Boone after 2018 Barkley Marathons from the Ginger Runner Live Podcast
• Interview with Eoin Keith and Ally Beaven after 2018 Barkley Marathons from the Talk Ultra Podcast
• Where Dreams Go to Die: Gary Robbins and the Barkley Marathons feature length documentary film