Neutrals, who are they?

Death Knights, perhaps... I was really hoping they would bring them back as an alternative to the Death Harbingers. It was one of my favorite units in Heroes of Might and Magic III.

Death Knights are a cool unit! It's a pity they didn't bring them back, and why were they removed in the first place? Many players (especially Necropolis fans) consider them one of the coolest units.