Glad you posted this!
Some favorites (at least, restricting myself to black-and-white films) are...
Hollywood classic era: Laura, Gun Crazy, Raw Deal, Ace in the Hole, The Set-Up, Act of Violence
UK classic era: Night and the City is an absolute favorite but there are plenty to choose from like They Made Me a Fugitive
France: Quai des Orfèvres, Retour de manivelle, gangster films by Jean-Pierre Melville
Japan: I am Waiting. There are plenty more great examples and I also want to highlight later b+w offshoots like The Most Terrible Time in My Life, Pitfall (Teshigahara 1962, not the 1948 US noir w Lizabeth Scott) and Shura (Pandemonium)
Argentina: Never Open that Door, The Nude Angel, Apenas un Delincuente
I'd consider Cairo Station (Egypt), Death is a Caress (Norway), and Death of a Cyclist (Spain) arguable examples of '50's international noir, seeing that many of the influences and situations that birthed noir in the US were echoed throughout the world.
I made a full noir list on MUBI called "Criminal Chiaroscuro," but I can't post links here yet.