Sylniq, the dark scholar

A half-elf wizard from Origination times, Sylniq studied every aspect of magic he could find. His curiosity took him to far reaches of the world, through ancient ruins and into subterranean depths. Eventually, his studies and experiments took him to dark places- he learned to defy death by absorbing the spirits' life-giving power and by consuming the souls of others, and transcended to lichdom. He now wanders the land as an immortal undead, continuing his search for lost knowledge. All who encounter him steer clear of him out of fear of having their soul devoured.
Not all who encounter Sylniq meet their fate. Those he allows to leave describe him as "egotistically merciful": he sees other humanoids as innocent lesser beings that he must occasionally feed on to survive, but doesn't always indulge. He ensures that those he spares are aware of the amount of restraint and mercy he has shown them, and seems to fancy himself a better person for it. He also occasionally leaves behind notes and markings in locations he visits, showing little respect for ancient sites he has investigated.
Zubie, the drunken halfling of Salmund, lost his family to Sylniq, and was compensated with a cursed gold coin that kept reappearing in his pocket.