Leo George Hertlein (1898 – 1972) was an American paleontologist and malacologist who studied the Recent and fossil mollusks of the eastern Pacific Ocean.
After graduating high school in Wichita, Kansas, he moved to the West Coast and entered the University of Oregon as a geology major.
In 1929, Hertlein was appointed assistant curator of the Department of Paleontology at the California Academy of Sciences.
In the 1930s, he traveled to the Galapagos Islands and the nearshore areas of Central America and Mexico.
He published over 150 papers on Recent and fossil mollusks, echinoderms, and brachiopods from California, Oregon, Washington, and Mexico.