According to Forbes, Smaug is the second richest person/creature this year, with an amassed fortune of $62billion. A hyperintelligent red-gold dragon known for complimenting thieves and liars for their "nice manners", he distrusts banks, swearing instead by the "plunder and hoard" investment style.
Other characters with a huge store of wealth include a prospecting duck who cheated in a bet ($51.9billion), a vampire with four hundred years of compound interest and an adopted daughter with an uncanny knack for predicting stock market trends ($36.3billion) and a morally dubious computer hacker from Sweden with eidatic memory ($2.4billion).
As to the richest person, I don't have a clue.