Nepenthe Productions and writer/director Martin Rosen (and animator Tony Guy) made two dark films with mature (serious-minded) subject matter - both based on Richard Adams' best-selling novels about animals and ecological concerns:
- Watership Down (1978), a bleak, allegorical animated fantasy film about the desperate quest of a warren of rabbits to find a new home, led by heroic Hazel (voice of John Hurt), a small, nervous rabbit named Fiver (voice of Richard Briers), and courageous Bigwig (voice of Michael Graham Cox). In the anthropomorphized tale, they must escape the destruction of their land during the construction of a housing development, and join a rival warren named Efrafa led by a vicious militaristic dictator, General Woundwort (voice of Harry Andrews). The film also included the last involvement in a motion picture for legendary actor Zero Mostel who played the cantankerous seagull Kehaar.
- The Plague Dogs (1982), the even darker, far more nihilistic, pro-animal rights film about two abused laboratory experiment dogs, a cynical, bitter black Labrador named Rowf (voice by Christopher Benjamin) and a brown and white dog named Snitter (voice of John Hurt). Both escape from captivity in a secret British government research lab (Animal Research, Surgical and Experimental) and become fugitives. While on the run, it is falsely reported and suspected that they carry the deadly bubonic plague and they are relentlessly pursued.
- the Adams' stories of the rabbits of Watership Down were retold in a short-lived animated TV series, produced by Rosen - 3 series of episodes aired beginning in 1999; with title music by Andrew Lloyd Webber
The French/Czech-made, science-fiction oriented Fantastic Planet (1973, Fr.) (aka La Planète Sauvage) possessed similarities to Fritz Lang's Metropolis (1927) with its two-tiered society on a faraway planet of Ygam, consisting of enslaved humanoids called Oms and a ruling class of bizarre, blue-skinned alien giants named Traags. It was based upon the popular French newspaper serial (Stefan Wul's Oms en Serie ("Oms by the Dozen")), and was lauded with the Cannes Film Festival's special jury prize, the Grand Prix, when it was first released. Its animation technique was to move paper cutouts across backgrounds.
The inventive animated fantasy Twice Upon a Time (1983), executive produced by George Lucas, told a story about two heroes and their friends who tried to prevent a maniacal madman from giving children nightmares. It used the same cut-out paper animation that South Park: Bigger, Longer and Uncut (1999), the most profane animated film (with 399 swear-words) would also later employ.