Karl Meltzer (born December 8, 1967, nicknamed "Speedgoat Karl") is an ultrarunner and ultrarunning coach based in Sandy, Utah. Meltzer has won more 100-mile ultramarathons than any other ultramarathoner, and has held speed records at major U.S. trails, including the Appalachian Trail and the Pony Express Trail. Meltzer's trail runs have been featured in news outlets from Ultrarunning.com to NBC Sports. Meltzer has been a professional ultramarathoner since 1999, and a coach since 2007.
While many ultramarathoners tend to be vegetarian, vegan, and anti-alcohol or caffeine, Meltzer has been seen with bacon, Red Bull, and microbrews.
On September 18, 2016, Meltzer set an Appalachian Trail record by completing the 2,190 miles over 14 states in 45 days 22 hours and 38 minutes. Meltzer's record was eclipsed in September 2017 by Joe McConaughy in a self-supported run. The current A.T. fastest known time was by Belgian runner Karel Sabbe, who completed the trail in 41 days, 7 hours, and 39 minutes on August 29, 2018.