Le Douanier Rousseau is a French Post-Impressionist painter, who is known for his unique style of depicting vivid, fantastical scenes. While the artist is commonly known as Le Douanier Rousseau, there are several other synonyms that have been used to describe him over the years. Some of the most popular synonyms include Henri Julien Felix Rousseau, Henri Rousseau, and simply Rousseau. Additionally, some have referred to him as a naïve painter or a self-taught artist due to his lack of formal training in art. Whatever name or adjective he uses, however, his legacy as one of the most important painters of the 20th century is undeniable.