In addition to his other villainies, the Joker is also a fan of IP. In the Batman Animated Series episode The Laughing Fish, the Joker fills Gotham Harbor with chemicals that give all the fish his characteristic grin, so that when fishers try to sell them (the fish are otherwise safe to eat) he can sue for copyright infringement. (In the original comic it was trademark infringement, which makes a smidgen more sense.) And in a later episode, Jokers Wild, he decides to destroy a Joker-themed casino because theyre cashing in on his image. Is there no end to his perfidy?
Given real-world IP laws, Im not sure why Warner Bros. allows these episodes to be hosted on YouTube or how long they will continue to do so; enjoy them while you can! (I like the earlier episode better because it has Harley Quinn in it. Everythings better with Harley!)