Who executed Topsy the elephant, why, and what was the connection between the execution and the War of the Currents?

Topsy had become something of a liability, having killed one man and, understandably, threatened others who abused her. Having failed to sell her, her owners decided to kill her with electrocution being chosen as the most humane method. An earlier suggestion of hanging had been vetoed. The connection to the 'War of the Currents' is less clear. Thomas Edison had nothing to do with the execution and the 'war' had been over well before the demise of Topsy. The electricity was supplied by a company bearing his name and was filmed by another company with the Edison name. Edison himself had nothing to do with the first company, and was not active in the second.

The story quoted in the first answer seems to be a myth, as is discussed thoroughly in this article: https://edison.rutgers.edu/life-of-edison/essaying-edison/essay/myth-buster-topsy-the-elephant

Apparently, Topsy was as hard to kill as Rasputin, but finally, chief electrician Hugh Thomas flipped a switch and 6600 volts did the job - a winch strangled her to make sure. There were a lot of people who wanted to watch. Later, they made umbrella holders out of two of her legs. What the hell is wrong with some people?

https://en.wikipedia.org/wiki/Topsy_(elephant)

Topsy the elephant was executed by her owners, Frederick Thompson and Elmer Dundy, the proprietors of Coney Island's Luna Park. She was put to death because she was deemed too volatile and dangerous after killing a spectator who had cruelly burned her trunk with a lit cigar.The connection between Topsy's execution and the War of the Currents is a widespread historical myth. While popular culture often claims Thomas Edison electrocuted Topsy to discredit alternating current (AC) power, historical evidence proves otherwise.