the Money Project: The Richest People in Human History (Part 1) [Link]. Obviously visit the site and zoom the image to get all the detail. I'll look forward to subsequent parts.
Obviously (as the write-up states) this is very difficult to get equivalence with more modern or present times and depends who you ask and what conversions etc are used but it does throw up some good bits: right place, right time backing the winner was Alan Rufus who William I made the 1st Lord of Richmond - a large chunk of northern England who - by "1086 he had become one of the richest and most powerful men of England" [Wiki]; or Solomon's wealth measured in trillions. And who had heard of Jakob Fugger, the Rockefeller of the 15th & 16th centuries; the "most influential businessman of all time"?