Willis Stanley Blatchley (6 October 1859, North Madison, Connecticut - 28 May 1940, Indianapolis, Indiana) was an American entomologist, malacologist and geologist. In his biological work, Willis Blatchley made contributions to the study of Coleoptera, Orthoptera, Hemiptera, and the freshwater molluscs of Indiana.
Though born in Connecticut, his parents moved to Indiana in 1860, the year after his birth. He attended high school in Bainbridge and enrolled at Indiana University in 1883, graduating with a B.A. in 1887 and an M.A. in 1891. There he worked under ichthyologist David Starr Jordan and geologist John Casper Branner. Blatchley received an honorary degree (LL.D.) from Indiana University in 1921. From 1887-1893 he taught at Terre Haute High School where he was Head of the Science Department from 1887-1893. From 1894-1910 he was State Geologist for Indiana. After being defeated for re-election in 1911, he retired from public office, but continued his natural history work as an amateur. Though much of his work focused on the fauna of Indiana, he traveled to Arkansas, Alaska, Florida, Canada, Mexico, and South America (1922-23).
Blatchley married Clara A. Fordice (or Fordyce?, 1854-1928), of Russellville, Indiana, on 2 May, 1882. They had two sons, Raymond Silliman Blatchley (11 February 1883 - 27 September 1953, Los Angeles, California--biography) and Ralph F. Blatchley (1885-1955, Dunedin, Florida; photo from Dunedin, Florida).
Blatchley described several new taxa.