Dan Muller (1889–1977) was an American artist, illustrator, and writer known for his vivid depictions of the American West. Born in 1889 in the Montana Territory, Muller grew up immersed in cowboy culture, working on ranches and participating in rodeos. This firsthand experience deeply influenced his art, which often portrayed cowboys, horses, and Western life with striking authenticity and movement.

Muller was largely self-taught and developed a distinctive style characterized by dynamic compositions and attention to anatomical detail, especially in his renderings of horses. His work appeared in magazines, book illustrations, and murals, and he also authored and illustrated books such as My Life with the Horse and Chico of the Cross Up Ranch.

Throughout his life, Muller remained dedicated to preserving the spirit and stories of the Old West. He spent the last 40 years or so of his life living and working in Wisconsin where he had a studio. He died in 1977, leaving behind a legacy of artwork that continues to resonate with Western art collectors and historians.