Karl Meltzer is an American ultrarunner from Sandy, Utah, who has won more 100-mile races than anyone in the history of the sport. Known as Speedgoat, he turned professional in 1999 and built his career on the mountain 100-milers of the American West, where his record includes six wins at the Wasatch Front 100 and five at the Hardrock 100, the most by any runner at either race.
His most productive season came in 2006, when he won six 100-mile races in a single year and was named Ultrarunner of the Year. He won five more in both 2007 and 2009, and by the end of 2021 his total at the distance stood at 45 victories. His Wasatch wins came in 1998, 2000, 2003, 2004, 2005 and 2006, with a best time of 19:43:47 in 2005. His Hardrock titles came in 2001, 2003, 2005, 2006 and 2009. He also won the Bear 100 three times, including the 2016 edition at the age of 48 on a rerouted course run in rain and snow.
Away from race courses, Meltzer set the supported speed record on the Appalachian Trail in 2016, covering 2,190 miles across 14 states in 45 days, 22 hours and 38 minutes. He had made an earlier attempt in 2008 that took 54 days. He has also set a speed record on the Pony Express Trail.
Meltzer has coached ultrarunners since 2007 and directs the Speedgoat 50K at Snowbird Ski Resort in Utah. Hoka named its Speedgoat trail shoe line after him.