Henri, also called "Uncle Horst", is the hidden secondary main antagonist of Madeline: Lost in Paris.
He is a French man, but at first, viewers (and Madeline and her friends) think he is from Vienna, Austria, as he claims. Sometimes, he would speak up when Madame LaCroque has not asked him, even finishing anything she was going to say.
He, saying to be Madeline's Uncle Horst, is first seen arriving at Miss Clavel's old vine-covered boarding school and gives some pieces of lace to the girls as a gift. He decides to send Madeline to a finishing school in Vienna. The next evening, he comes over to stay for dinner and a performance (in hopes that he finds out that their school does as well as any finishing school). It impresses him, but he doesn't change his mind.
The next morning, Uncle Horst starts taking Madeline to the finishing school, but (at first) refuses to allow Genevieve, the dog, to come. But after Madeline said no dogs in the school in Vienna meant she wouldn't go there either, he agrees to let her come; however, he does not allow her to come onto the subway due to being a dog. He didn't even list his name at all, much to the dismay of Miss Clavel. He then stops at a lace shop where he accidentally reveals that he is not Viennese as he claims, but rather, French, nor is he Madeline's Uncle Horst, but a failed Shakespearan actor named Henri. He takes her down into the factory, where Madeline meets Henri's boss, LaCroque.
Later, while Henri is carrying Madeline's suitcase, he runs away when the police arrive. Although Henri reveals his true name, Miss Clavel proves he is the man who took Madeline away using the suitcase. He is forced to show the police and Miss Clavel where Madeline is. Later, when he tries running away in the factory, LaCroque kicks him by mistake, and he gets tied up with the thread. He and LaCroque are then arrested by the police.