Demian: The Story of Emil Sinclair's Youth (1919) is a semi-autobiographical novel by German writer Hermann Hesse. Demian was published in the aftermath of World War I and grew out of Hesse's experience of psychoanalysis with Carl Jung and J. B. Lang.

The novel is set in Germany in the decade preceding World War I, roughly 1904 to 1914. Narrated by Emil Sinclair, Demian describes Sinclair's personal inward journey to a genuine understanding of his deep inner self. The character Max Demian, Sinclair's schoolmate, helps to open Sinclair's mind to unconventional ways of thinking that ultimately lead to self-discovery. Through his years of grade school, high school, and university education, Sinclair encounters several personal teachers who lead him toward a revelation of true self-knowledge. The novel ends during World War I, when both young men have been wounded in battle.

Demian applies concepts of Jungian psychoanalysis in a strongly symbolic narrative drawing from Christian theology, Nietzschean philosophy, and Eastern mysticism. Demian struck a chord with Germany's postwar youth, who felt it expressed a common search for personal identity. Hesse's novel also resonated with a generation of youth in the United States during the 1960s and 1970s.