What is the most downbeat or nihilistic ending to a film you've seen?

[Verisimilitude1984]

I'm not normally one who gravitates towards such films but it got me thinking - particularly after watching a documentary on 1970s movies, which is where many were noted for this. I've also been watching some noir and neo-noir.

I'd have to say David Mamet's 1991 film 'Homicide' as the darkest ending I can recall. The protagonist Bobby Gold by the end of the film

[Show spoiler]discovers that he has been played by those who he felt the deepest connection too in the Jewish community, spurning his desire to reconnect spiritually when he is effectively outed as a racist. By his actions, he loses his partner, very nearly his life, his faith, his job and relationships with his peers. He effectively doesn't have any hope in humanity as the film ends.

If that takes number one spot, honourable mentions are Serpico, Invasion of the Body Snatchers (1978), The Empire Strikes Back, The French Connection, The Godfather Part III, Double Indemnity, Body Heat.