New common hostile night/darkness mob

Last one was added many years ago (Not counting phantom, drowned, husk or stray. Phantom has too specific and irregular spawning, drowned is localised to oceans/water and husks/strays are just variants and they are localised to biomes).

These mobs are so important and yet over the years they became repetetive and even boring, adding new unique one (with the rarity of zombies/skeletons/spiders/creepers, not uncommon like endermen and witches) would add quite the flavor to nights, caves and other unlit areas.