Mount Barnard is a mountain in the U.S. state of California, and has the dubious distinction of being the highest thirteener, a peak between 13,000 and 13,999 feet (3,962 and 4,267 m) in elevation, in the United States. It is located on the Sierra Crest and straddles the boundary between Tulare and Inyo counties about 2 miles (3 km) southwest of Mount Williamson, the second-highest peak in the state; Mount Barnard is the twelfth-highest.

The first ascent was by W. L. Hunter, John Hunter, William Hunter and C. Mulholland on September 25, 1892. They named the peak in honor of E. E. Barnard, a noted astronomer.