6. William the Conqueror (Wealth: $209B)
William the Conqueror Born in Normandy, France, William the Conqueror led the invasion of England and was instated as the first Norman king of England after King Harold and his brother were killed in the Battle of Hastings. He reigned in England for 21 years (1066-1087) where he was known to acquire vast properties, which were also distributed to his fellow Normans. During his time, William the Conqueror was able to amass nothing less than $209B in wealth.