Mount Pennell is a prominent 11,413-foot (3,478 m) elevation summit located in eastern Garfield County, Utah, United States.

[5] Almon Harris Thompson served as chief topographer and geographer of John Wesley Powell's Second Geographical Expedition (1871–1875) when he named Mount Ellen after his wife, Ellen Powell Thompson, and Mount Pennell was later named for his friend Joseph Pennell (1857–1926), an American artist and author.

[5][6] The American geologist Grove Karl Gilbert surveyed this area in 1875 and 1876, and published his findings in 1879 as a monograph, The Geology of the Henry Mountains.

The term laccolith was first applied as laccolite by Gilbert after his study of intrusions of diorite in the Henry Mountains.

This desert climate receives less than 10 inches (250 millimeters) of annual rainfall, and snowfall is generally light during the winter.