The characters in this beautiful story sketch from Sleeping Beauty are depicted in dark silhouettes. The final frame from this sequence doesn't go as far, standard colors were used instead. This type of staging reminds me of the incredible work by German animation pioneer Lotte Reiniger (1899 - 1981)
In 1926 she completed her animated feature The Adventures of Prince Achmed. All done in silhouette animation. Just astounding. You can read her life's story in this Wikipedia page:
Disney of course applied this aesthetic in certain scenes for numerous films like Bambi and Fantasia. There is something pure and beautiful about animation in silhouette. You don't have the subtleties of interior drawing and definition. Everything is communicated through body language.
A while ago a analyzed the importance of a clear silhouette in traditional animation: