Solomon Llewellyn Cobb

No one has actually met Solomon Llewellyn Cobb.
Honestly, no one you'll ask even knows exactly where to find him. Some rumors say he lives in one of the ziggurat-estates of Kaza'ir, the guest of a notable magister. Others state that he has a secret library in the sewers of Keleboros. Some say he lives in the far flung reaches of frozen Nordmark, in a remote keep in the wilderness. And yet no evidence of a living-place has yet been produced. Some say he's dead, and his library was ransacked decades ago.
All that's known of Solomon Llewellyn Cobb is that he is, or was, a book collector. Or a writer. Perhaps both.
Every now and then, a tome will turn up somewhere in Mesothalassos with a distinctive silver name-plate on the inside cover: From the Library of Solomon Llewellyn Cobb.
All else that's known is that if you come across one of these books, treat it with suspicion.
Most books found that once spent time in his libary are mundane enough, though still arcane and esoteric. Books on magic, the gods, the creation of Nadmir, astronomy, alchemy, and other such academic topics, are common. But Cobb is not known for collecting these.
He is known for collecting forbidden books. Cursed books. Books that you want no part of.