I'm nominating " Grave of the fireflies "

Melancholia or Nil By Mouth.

"Bei Nacht und Nebel"

Fatfather

Singin' in the rain.

I would call "Grave of the Fireflies" the saddest film I have ever seen. Not sure if depressing is quite the word I would use.

The Road

Not sure about 'of all time'...but certainly dark.

https://youtu.be/bO8EqMsxOiU

Citizen Kane.

A classic, but drains the spirit.

I saw a JAV movie where an office full of Japanese secretaries took a sex potion and took on the male boss one by one. That was depressing.

Lucky b******

Sophie's Choice

Irreversible

Elephant Man or Banbi....I cant decide.

Grave of the Fireflies

The Plague Dogs

Schindler's List

Requiem for a Dream

Filth

Forrest Gump

It's a toss-up for me.

Ordinary People

It's My Party

I would call "Grave of the Fireflies" the saddest film I have ever seen. Not sure if depressing is quite the word I would use.

No way, that film took me like a month to recover from along with lilja 4 ever, Definitely depressing. Extremely sad also.

It's a toss-up for me.

Ordinary People

It's My Party

Ordinary people is one I've never got round to watching. Might give it a shot this weekend.

Any film with Arnie and Sylvester. They are just over muscled freaks who cannot act, and should never be near a movie set.

Elephant Man

One Flew Over the Cukoos Nest

Kramer v Kramer

Grapes of Wrath

Beaches

The Ugly American

The Quiet American

Good Morning Vietnam

Apocalypse Now

The Year Of Living Dangerously

They Shoot Horses Don't They?

Actually I need to add ''Dancer in the dark '' to this especially the ending. Harsh.

Stalingrad

Safe

Anti-Christ

I was going to post this in "Favourite British Films" but it's maybe more suitable here

Brazil, by Terry Gilliam

Don's Party an Auzzie flick

I'll tell you a harsh film which is underrated but could be classed as depressing is "Assault on Wall Street" definitely worth the watch.

The champ.

ET

The champ.

I think you've nailed it there mate. Can't believe I forgotten about that one