Gwen, or the Book of Sand () is a 1985 French animated science fiction film written and directed by Jean-François Laguionie, using gouache. It is alternatively known as Gwen, Gwen and the Book of Sand, Gwen, the Book of Sand and similar variations.
Gwen is a young girl adopted by a nomad tribe in a desert post-apocalyptic world. In the desert, where only few animals, like ostriches or scorpions, can survive, a mysterious entity regularly drops gigantic replicas of everyday life objects from our world, such as bags, telephones, clocks and armchairs. When a young boy, Gwen's friend, is kidnapped by said entity, Gwen and an old woman called Roseline start on a trip to bring him back. They eventually encounter other people living in an isolated city and preserving remains of the old civilisation in strange ways.
The film won the Grand Prix de la critique at the Annecy International Animated Film Festival.
The film was released in the United States as an Ultra HD Blu-ray by Deaf Crocodile Films in 2025, marking the film's first official American release.