King Arthur Castle is a prominent Grand Canyon summit in northern Arizona, rising 7,344 feet in the Shinumo Amphitheater among nearby landforms with Arthurian names. Its dramatic relief above the Colorado River and layered rock profile reflect classic canyon geology, from Kaibab Limestone and Coconino Sandstone at the top to older formations exposed lower down. The name grew from an early Grand Canyon naming tradition that favored mythological and heroic figures; cartographer Richard Tranter Evans applied it in 1902 while mapping the area, and the U.S. Board on Geographic Names officially adopted it in 1908. The summit later attracted notable climbers, including first ascentionist Merrel Clubb and Harvey Butchart.