I've mentioned Farmer Brown on this blog before, in the Batman: The Animated Series super post, but the information was not complete until now, so he gets his own page!
Farmer Brown was a one-time villain in The New Batman Adventures. He first appeared in the episode "Critters" (September 1998), and despite his name and appearance, he's a genetic engineer who created mutant farm animals to terrorize Gotham.
Although he hasn't yet had a proper first appearance in comics, his name and likeness HAVE appeared. In Batman: Streets of Gotham #4 (September 2009), his name and likeness appear.
The issue is about a guy named The Broker who acts as a real estate person for supervillains. When Zsasz tells him he's in the market for an abattoir, the Broker sells him Farmer Brown's old pork factory.