The Adventures of Prince Achmed (1926)

The Adventures of Prince Achmed (German: Die Abenteuer des Prinzen Achmed) is a 1926 German animated fairytale film by Lotte Reiniger. It is the oldest surviving animated feature film; two earlier ones were made in Argentina by Quirino Cristiani, but they are considered lost. The Adventures of Prince Achmed features a silhouette animation technique Reiniger had invented which involved manipulated cutouts made from cardboard and thin sheets of lead under a camera. The technique she used for the camera is similar to Wayang shadow puppets, though hers were animated frame by frame, not manipulated in live action. The original prints featured color tinting.

Several famous avant-garde animators worked on this film with Lotte Reiniger, among them Walter Ruttmann, Berthold Bartosch, and Carl Koch.

The story is based on elements taken from the One Thousand and One Nights, specifically "The Story of Prince Ahmed and the Fairy Paribanou" featured in Andrew Lang's Blue Fairy Book.
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Probably the oldest full length animated feature film. If the style looks familiar it just shows how far ahead of its time or better yet, how timeless, The Adventures of Prince Achmed is.