Douglas Edward Gretzler (May 21, 1951 – June 3, 1998) was an American serial killer who, together with accomplice Willie Steelman, committed seventeen murders over a three-week period in October and November 1973 in the states of Arizona and California. All the victims were shot, strangled, or stabbed to death, and the majority of the murders were committed in the commission of robberies or for the purpose of eyewitness elimination.