The mountain is named for its three distinct peaks along the summit, forming the cirque that is now part of the Mount Hood Skibowl ski resort.[4]
The highest peak has an elevation of 5,070 feet (1,545 m). The name was in use as early as 1897, according to Elijah "Lige" Coalman, the namesake of Coalman Glacier.[4] The mountain has also been called "Tom Dick Mountain" in the past, although the Board on Geographic Names officially decided in favor of including "Harry" in 1969, making the mountain's name a play on the phrase "Tom, Dick and Harry".[3] It has frequently been noted on lists of unusual place names.[5]
Mirror Lake, a popular hiking destination, is located on the north side of the mountain.