Not counting any monster from MHW as "boss fights", since I could easily fill this list with those fights
10.- Bloodless - Bloodstained
9.- Sword Saint Ishin Ashina - Sekiro
8.- Sigrun - God of War
7.- Mantis Lords - Hollow Knight
6.- The Nameless King - Dark Souls 3
5.- Gehrman the First Hunter - Bloodborne
4.- Grun - Nier: Automata
3.- The Hollow Knight/Pure Vessel - Hollow Knight
2.- Beauvoir - Nier: Automata
1.- Lady Maria of the Astral Clocktower - Bloodborne
Honorary Mentions
Dark Beast Ganon - Breath of the Wild
Ludwig - Bloodborne
Slave Knight Gael - Dark Souls 3
Urizen - Devil May Cry 5
Alraune - Bayonetta 2
Cornell - Lords of Shadows
A bunch of others, they keep coming...
Honestly, I think I could also make this list about Bloodborne alone, those are some of the boss fights I've enjoyed the most this last decade. Most of them are very memorable.
Ill maybe edit later if I remember any other worth to make the list, this were the ones that came to mind. Theres many.
