The Joker is probably the worst criminal in the history of fiction. He’s a mass murderer, a gaslighter, and has inspired crimes against method acting, and that’s just the short list. The full list, at least in the Batman: Arkham series, is longer. Much, much longer.
Batman: Arkham VR allows players, among other things, to poke around the Batcomputer and learn more about Batman’s many adversaries. That includes a list of the Joker’s crimes, some of which you’d expect: Homicide, kidnapping, and the like. But, as the list of his convictions keeps going, it gets stranger and stranger. It turns out that in the DC Universe failing to properly restrain a rhino is a felony you can be convicted of, that the Joker has an unusually intense interest in making animals fight each other, that he’s actually murdered royalty, and one string of convictions, namely “desecration of a corpse,” “improper disposition of a body,” and “improper labeling of meat products,” are hopefully separate cases. Otherwise that sure sounds like the Joker turned a stiff into lunchmeat.
So, yes, in at least one continuity, the Joker is an enthusiastic abuser of animals and has probably eaten at least one person. But at least his boss fights are less annoying than Deathstroke’s.