Théophile Steinlen was a French-Swiss painter and illustrator known for his vibrant depictions of Parisian life during the Belle Époque in the 19th and early 20th centuries. He gained fame for his iconic poster for the Moulin Rouge and often portrayed everyday scenes, focusing on working-class people, animals, and the lively streets of Paris. His distinctive style combined strong lines, rich color, and a dynamic sense of motion, offering a vivid snapshot of the time's social fabric.