Mount Ellsworth is an 8,235-foot summit in the Henry Mountains of southern Utah, west of Glen Canyon National Recreation Area in remote, arid Garfield County. Its rugged setting helped make the Henry Mountains important to geology after Grove Karl Gilbert surveyed the area in 1875 and 1876 and published The Geology of the Henry Mountains in 1879. His study of diorite intrusions there introduced the term laccolith, first written as laccolite, a concept closely tied to the range. The mountain's name appeared on an 1875 map, though its origin is uncertain, and the peak remains defined by elevation, dryness, and isolation.