Astérix et la Serpe d'Or (lost animated comic book-based film; 1967)
In 1967, editing company Dargaud and animation studio Belvision adapted the first album of the popular Asterix series into the animated movie Asterix the Gaul. This was done by the companies's editor and CEO without the knowledge of Asterix creators René Goscinny and Albert Uderzo, who only found out about it after completion.
At the same time, Dargaud and Belvision were already working on an animated movie adaptation of Astérix et la Serpe d'Or ("Asterix and the Golden Sickle" in French), the second book in the series. An adaptation of Asterix and the Big Fight was also intended.
However, Goscinny and Uderzo were displeased by how the first movie turned out; they asked for production on the sequels to be ceased, and for all work already done on the Golden Sickle animation to be destroyed. To this day, there is no known trace of this cancelled/destroyed animated Asterix sequel. Asterix and the Big Fight would eventually get an animated feature adaptation in 1989.