Dark Knight:-
This Knight spawns when a dark knight's spirit kill a cursed knight and possess it. This boss will drop its armor and a knight sword which can cause paralysed effect to the enemy
Troll:-
These spawn rarely during night. They can cause a heavy amount of damage when they are near so it is better to keep them in range and using projectile. It drops it’s hammer upon death
Chopper Knight:-
This Knight can spawn rarely when a dark knights spirit possess a cursed knight. It will drop it helmet upon death which can be used to fly
Inferno, The Emberlord:-
Inferno will spawn in a rare structure in nether named "inferno dungeon". He may drop hardened ember and its sword which can summon exploding blocks above enemies ( Sometimes his drops may get destroyed)