Microsoft founder Bill Gates is worth an estimated $85.7 billion. Chip Somodevilla / Getty There are two types of billionaires: those who inherited their wealth, and those who built it from nothing.

Our friends at Wealth-X, a firm that does research and net worth valuations on ultra-high net worth individuals, focused on the latter to compile a list of the wealthiest self-made billionaires in the world.

From tech mogul Bill Gates to Alibaba founder Jack Ma, here's who made the list.