Eva Dugan (1878 – February 21, 1930) was a convicted murderer whose execution by hanging at the state prison in Florence, Arizona, resulted in her decapitation and influenced the state of Arizona to replace hanging with the lethal gas chamber as a method of execution.

Born in Salisbury, Missouri, in 1878. Dugan later married and had two children (a son and a daughter) but her husband abandoned the family, leaving them destitute. Dugan relocated to Juneau, Territory of Alaska, after trekking north during the Klondike Gold Rush of 1896–1899 and became a cabaret singer and worked as a prostitute to support herself and her children. Many years later, she moved to Pima County, Arizona, where she worked for an elderly chicken rancher, Andrew J. Mathis, as a housekeeper.

Dugan became a live-in housekeeper of Andrew J. Mathis, wealthy owner of a chicken ranch. Very quickly the employer/employee relationship became cantankerous. The two often bickered with each other because Mathis hated Dugan's cooking and wasn't satisfied with her work and Mathis was demanding, abrasive and difficult to get along with. Mathis fired Dugan and told her to leave his property by morning. The next morning, January 23, 1927 Mathis disappeared, as did some of his possessions, his Dodge coupe automobile, and his cash box. Neighbors reported that Dugan had tried to sell some of his possessions before she disappeared as well.