An undead nobleman from the cursed house of "Dunwiche."
He was a 5e ranger but my DM allowed me to replace all the magic with necromancy spells of the same level.
I played him like a Dark Souls npc, it was fun. Covered in rags and a helmet, keeping his identity a close secret, continuing his unlife by stealing the remaining life out of his victims while he retrieved his arrows, all the while using the party as a means to find and end the his family's curse.
After the campaign, which did not end in his favor, the DM kept him as an recurring npc encounter and built up a mythos around him, the boogeyman that would steal your life in your sleep kind of thing.