Charles Willison Johnson (October 26, 1863 – July 19, 1932) was an American naturalist who specialized in entomology (especially Diptera) and malacology, making significant contributions in both fields. He was a mentor and inspiration to many students and young scientists such as William J. Clench (who founded a publication named Johnsonia in his honor). Johnson was Curator of the Wagner Free Institute of Science, 1888–1903, then was Principal Curator at the Boston Society of Natural History, 1903–1932.