Have you read the Englehart/Rogers run of Batman (the most famous part is "The Laughing Fish"), which was collected in Batman: Strange Apparitions? That and Prey really solidified Hugo as a major threat who was barely used anywhere else. He's kind of a cult villain, I think, as he's only appeared in a handful of stories, most of which are very well-regarded.

I will do my best in the posts, but Prey is so good that I shudder to consider what I'll have to cut to keep it under the 1/3rd limit.