The most apocalyptic ending to a film?
The ending to the director's cut of 1986's "Little Shop of Horrors."
shareI'm not well versed in this genre nor have I seen "Little Shop of Horrors" but the ending to 'The Machine War' in the "Animatrix" was a haunting experience. Not only did people lose their sense of humanity but the machines themselves lost the very thing they were fighting for, a sense of purpose and belonging, the right to exist, all thrown away in the pursuit of fiery vengeance and anger in retaliation for the hostility they received from humans who had grown afraid of them.
shareExcellent example.
I also want to throw in there "Melancholia" and "Invasion of the Body Snatchers" (the '78 version).