Millie Marotta is a British illustrator and author known for her intricate and detailed coloring books. Her work often features themes from nature, including animals, plants, and landscapes, inviting creativity and relaxation for those who color her designs. Her popular books, such as Animal Kingdom and Tropical Wonderland, have gained a large following, appealing to both adults and children. Marotta's illustrations are characterized by their fine lines and whimsical style, making them a favorite among coloring enthusiasts looking for a creative outlet.