It's been going around on my facebook/internet in general that Thomas Edison launched a campaign where he electrocuted animals to demonstrate the dangers of AC. Is this true?
I know an elephant named Topsy was killed by electrocution but I don't know if it was just because it needed to be put down or there was an additional motive there (some attack on AC).
Most of it is false, some has truth.
The person who electrocuted animals was Harold Pitney Brown, a self styled anti-AC crusader. AC at that time was transmitted at very high voltages in badly insulated wires over public streets and many people were electrocuted by it. Brown thought AC was a public menace and went after it in the press and at public and government meetings. Brown used Edison's lab to perfect an animal demonstration (electrocuting dogs) to back his claim that, even at low voltages, AC was more dangerous than DC. According to historian Bernard Carlson in his book titled "Innovation as a Social Process: Elihu Thomson and the Rise of General Electric" Edison Electric Light treasurer Francis S. Hastings came up with the idea of using Brown and his experiments to slander Westinghouse's AC system as dangerous. So long, involved, and not actually Edison himself.
Topsy had nothing to do with this or Edison, War of the currents was 1888-1892, ending with all the companies involved going AC. Topsy was killed in 1903, the debate over AC was long over and she was killed in an unrelated Coney Island stunt, the only motive was greed on the part of her owners. There is a whole book written about the life of Topsy and you can also read the Rutgers University page about it.