Crazy Louie is a minor/background character in Back at the Barnyard. He is a crazy man who is the groundskeeper of a golf course. He is close friends with Otis and his friends, not caring that they're talking animals, due to his insanity.
In his first appearance, "Cowdyshack", while Otis and his friends were playing on his golf course, Pig accidentally damages his appendix with a golf club, seemingly putting Louie at risk of death due to his appendix already being weak, so Otis and his friends play in a golf tournament to win him a new appendix, while Abby nurses Louie, as the poor man gets gradually loopy while nearing the end.
After Pig wins the tournament for Otis after the latter got injured, Louie realizes that the appendix is actually useless to his body, so he sells it to have extra thumbs surgically added to him, much to the animals' horror.
He appears as a background character in later episodes, such as "Udderado" and "Free Schmoozy".
He was originally voiced by Tom Kenny in "Cowdyshack", while he was voiced by Rob Paulsen in "Udderado".