On September 29, 1916, American oil tycoon John D. Rockefeller became the world's first billionaire. An excerpt from the article:
"An American businessman became the world’s first billionaire in 1916. Today, the USA may comprise the most number of billionaires, but the status quo of ‘billionaire’ was introduced by John. Back then, he was setting records with his wealth. His net worth over the last decades of his life would easily place him as the wealthiest known person in history. As a percentage of the United States’ GDP, no other American fortune – including those of Bill Gates or Sam Walton – would even come close to John D Rockefeller."