Robert Allen Cooley (27 June 1873 - 16 November 1968) was a US entomologist. Born in Deerfield, Massachusetts, he studied at Massachusetts Agricultural College and worked at Montana State College. He was appointed the first state entomologist for Montana in 1903, and worked on Rocky Mountain spotted fever, studying the life cycle of the tick that transmits the Rickettsia bacteria that cause the disease. He also worked on the eradication of the disease, and from 1931 until his retirement in 1946, he was head entomologist at the Rocky Mountain Laboratory, Hamilton, Montana, where the vaccine was developed. Cooley died at the age of 95 in Hamilton. The Cooley Laboratory at Montana State University is named in his honour.