Franz Stassen was a German painter and illustrator.

Educated at the Berlin University of the Arts, Stassen worked within the German Jugendstil tradition, inspired by artist such as Max Klinger, Gustav Klimt and other symbolist painters. He is best known for illustrating the works of Richard Wagner, particularly Der Ring des Nibelungen and Parsifal. Stassen was a friend of Wagner's son Siegfried and closely associated with the nationalistic Bayreuth Circle, centered around the Bayreuth Festival.

His Wagner illustrations were popular in Wilhelmine Germany and widely reproduced. They have been said to anticipate the heroic American Comic book style. His elaborate incorporation of musical staves and leitmotifs into his illustrations have also been commented upon.

In addition to his Wagnerian works, Stassen created illustrations for The Brothers Grimm's Fairytales, Goethe's Faust and Hans von Wolzogen's Die Edda, Germanische Götter- und Heldensagen among other literary subjects.