Walter Flex, 1887-1917, was a German author responsible for Wanderer zwischen beiden Welten (The Wanderer between Two Worlds), a stunning war novel dealing with themes of humanity, friendship and suffering during World War I.

Born in Eisenach to a secondary school teacher, he went to the University of Erlangen where he studied German, thanks to the award of a bursary. In his brief life prior to the outbreak of war he worked as a teacher, publishing, amongst other works, Das Volk in Eisen and Sonne und Schild, a series of well received nationalist works. As a song, his poem Wildgänse rauschen durch die Nacht gained popularity with the Wandervogel youth and was well known and sung in Germany until the 1970s.

He served as a soldier from 1914, having enlisted as volunteer at the outbreak of war, was injured in action and died on October 16, 1917 at Oti Manor, Saaremaa, Estonia.

His Wanderer zwischen beiden Welten was published in 1916, by Beck's Verlag, and was well received. His reputation grew in the post-war years and his romantic idealism was exploited by the Nazi party, who found his evocative and romantic lyricism especially appealing and considered it an expression of Aryan ideals.

During the time of and partly due to German student movement his reputation faded almost entirely.