William Kemmler (May 9, 1860 – August 6, 1890) of Buffalo, New York was a convicted murderer and the first person to be executed using an electric chair.
Kemmler murdered Tillie Ziegler, his common-law wife, with a hatchet on March 29, 1889, and was sentenced to death by electrocution at New York's Auburn Prison. His lawyers appealed, arguing that electrocution was cruel and unusual punishment. George Westinghouse, one of the backers of alternating current as the standard for the distribution of main power, supported his appeal. The appeal failed, partly due to the support of Thomas Edison for the state's position (Edison was a backer of direct current power supplies, and it is speculated he wanted to use the publicity surrounding the electric chair to convince people that AC was dangerous).
The practical details of the chair were finalized by the first State Electrician, Edwin Davis.