You can post your own below. I'll only do one film per director.
1920s:
The Phantom Carriage (1921) - Victor Sjöström
1930s:
The Story Of The Last Chrysanthemums (1939) - Kenji Mizoguchi
1940s:
Day Of Wrath (1943) - Carl Dreyer
1950s:
Early Summer (1951) - Yasujiro Ozu
1960s:
The Cloud Capped Star (1960) - Ritwik Ghatak
1970s:
Jana Aranya (1976) - Satyajit Ray
1980s:
The Sacrifice (1986) - Andrei Tarkovsky
1990s:
Taste Of Cherry (1997) - Abbas Kiarostami
2000s:
Yi Yi (2000) - Edward Yang
2010s:
Amour (2012) - Michael Haneke
2020s so far:
Close Your Eyes (2023) - Victor Erice
This is my opinion. You can drop your own favourites below.
1920 Metropolis
1930 Beau Geste
1940 Casablanca
1950 The Seven Samurai
1960 2001 A Space Odyssey
1970 Chinatown
1980 Das Boot
1990 The Lion King
2000 Gladiator
2010 Hacksaw Ridge
2020 NAZA
1970s : Alien/One Flew Over the Cuckoo's Nest
1980s : Blade Runner
1990s Pulp Fiction/Amelie Poulain
2000s Wall-E
2010s Drive