The Gilded Age brought unprecedented levels of wealth and success to a select group of American entrepreneurs. Historians have long debated whether these men were captains of industry or robber barons, a derogatory term which suggests that they got rich by exploiting those below them.

To answer this question, let's take a look at John D. Rockefeller, the country's first billionaire. Rockefeller had a humble background and entered the workforce as a shipping clerk. When Edwin Drake discovered oil in Pennsylvania in 1859, Rockefeller saw an opportunity and refocused all of his money and interests into this new industry. In a few short years, Rockefeller completely revolutionised the oil refinery process by introducing new techniques. To eliminate waste, he sold off the by-products of kerosene, namely petroleum jelly, to candlemakers and medical supply companies. He even sold the waste from the jelly to companies who paved America's roads. In this respect, Rockefeller's reforms made him a true captain of industry.

However, Rockefeller's business practices kept his profits soaring while smaller oil companies crumbled. He was also criticised for paying low wages to his workforce and getting rich at their expense. To some extent, then, Rockefeller was very much a robber baron but his philanthropic activities should be considered too; before his death in 1937, he gave away almost half of his fortune to charity.