The War of Currents ... And The Sparking Deaths of Topsy And William Kemmler

An image from Thomas Edison's film Electrocuting an Elephant, 1903

Wiki:

In the "War of Currents" era (sometimes, "War of the Currents" or "Battle of Currents") in the late 1880s, George Westinghouse and Thomas Edison became adversaries due to Edison's promotion of direct current (DC) for electric power distribution over alternating current (AC) advocated by Westinghouse and Nikola Tesla ....

.... Edison carried out a campaign to discourage the use of alternating current, including spreading information on fatal AC accidents, publicly killing animals, and lobbying against the use of AC in state legislatures. Edison directed his technicians, primarily Arthur Kennelly and Harold P. Brown, to preside over several AC-driven executions of animals, primarily stray cats and dogs but also unwanted cattle and horses. Acting on these directives, they were to demonstrate to the press that alternating current was more dangerous than Edison's system of direct current. He also tried to popularize the term for being electrocuted as being "Westinghoused". Years after DC had lost the "war of the currents," in 1902, his film crew made a movie of the electrocution with high voltage AC, supervised by Edison employees, of Topsy, a Coney Island circus elephant who had recently killed a man.

Edison opposed capital punishment, but his desire to disparage the system of alternating current led to the invention of the electric chair. Harold P. Brown, who was at this time being secretly paid by Edison, constructed the first electric chair for the state of New York in order to promote the idea that alternating current was deadlier than DC.

When the chair was first used, on August 6, 1890, the technicians on hand misjudged the voltage needed to kill the condemned prisoner, William Kemmler. The first jolt of electricity was not enough to kill Kemmler, and only left him badly injured. The procedure had to be repeated and a reporter on hand described it as "an awful spectacle, far worse than hanging." George Westinghouse commented: "They would have done better using an axe."