If you were to ask 100 people outside of Oklahoma or North Dakota who Harold Hamm is, you'd probably get 95 blank stares. And yet the founder of Continental Resources (NYSE:CLR) -- and billionaire 20 times over -- has probably done more to strengthen America's position in the global oil business than any other individual. Hamm owns 68% of Continental, which he founded more than 40 years ago, but it wasn't until about a decade ago that Continental hit it big, using hydraulic fracturing and horizontal drilling to finally unlock North Dakota's massive shale oil deposits. 

The explosive growth that Continental has led in North Dakota's Bakken formation has had a big impact on a Berkshire Hathaway subsidiary, too, netting more than $10 billion in profit for that company. For details on that and Harold Hamm's true "rags to riches" story, check out the slideshow below.