Bailey Willis (March 31, 1857, in Idle Wild-on-Hudson, New York, United States – February 19, 1949, in Palo Alto, California) was a geological engineer who worked for the United States Geological Survey (USGS), and lectured at two prominent American universities.
He also played a key role in getting Mount Rainier designated as a national park in 1899.
After later focusing more on seismology, he became one of the world's leading earthquake experts of his time.