There’s rich, there’s wealthy, and then there’s John D. Rockefeller. Considered by many to be the most financially-prosperous individual in modern history with an estimated $900,000,000 bank balance (unadjusted for inflation) in the early 1910s, Rockefeller (1839-1937) made his massive fortune by dominating the oil industry. While Rockefeller was prone to controversy—he was accused of being a monopoly in the fuel business—he was also a generous philanthropist, donating over a half-billion dollars in his lifetime (and that's also unadjusted for inflation). Take a look at some things you might not have known about the legendary tycoon.

1. HIS DAD PRETENDED TO BE A DOCTOR.

While his son would go on to want for nothing in life, William Avery Rockefeller was not a man of resources. The one thing he could depend on was a somewhat diabolical gift for conning others. Before his son was born, William spent time as an itinerant, going from place to place pretending to be deaf and soliciting free meals. (Eliza, the daughter of one such target, became his wife and John’s mother.) In other towns, he would hand out sheets referring to himself as “doctor” and pretend to have found a “cure” for cancer. The elder Rockefeller also insisted that his mistress, Nancy, live in the same house as his family, where she bore him two children. William Rockefeller would continue peddling “medicines,” sometimes under the pseudonym of William Levingston—and when he died in 1906, that was the name on his tombstone.

2. HE CELEBRATED HIS OWN PERSONAL HOLIDAY.

More important to Rockefeller than his own birthday was what he called “Job Day.” The future oil magnate was born and raised in upstate New York and took on his first real job at the age of 16 for a grain and coal supplier/shipper after his family relocated to Cleveland, Ohio. The date he started—September 26, 1855—was when Rockefeller believed he got his official start in business. As an adult, he celebrated the day every year.

3. HE DID EVERYTHING HE COULD TO DOMINATE THE OIL INDUSTRY.

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Rockefeller’s wealth was a consequence of his obsession with owning the oil industry. He struck deals with railroads to ship his goods cheaply, bought out smaller companies, and helped usher in the concept of a monopoly in modern times. Smaller businesses were faced with a choice: be consumed or attempt to compete with his massive corporation. His buying spree was referred to as the “Cleveland Massacre.” By 1882, his company, Standard Oil, owned or controlled 90 percent of all refineries in the United States. “Competition is a sin,” he was allegedly quoted as saying.

4. HE HIRED A STAND-IN SOLDIER TO SERVE FOR HIM IN THE CIVIL WAR.

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Due to be drafted to serve the Union in the Civil War in 1863, the 23-year-old Rockefeller did what many men of means had done: He paid for someone to serve in his place. This practice was allowed by the U.S. government, which granted draftees the ability to offer up a substitute. No record exists of who the man who took Rockefeller’s spot was. His brother, Frank, chose to serve at age 16, telling a recruiting sergeant he was 18. Despite being wounded in battle, he survived.

5. HE HELPED REDUCE HOOKWORM IN THE UNITED STATES.

With his fortune, Rockefeller pursued a number of philanthropic efforts in his lifetime. In 1910, that funding led directly to the widespread treatment of a mostly-forgotten illness: hookworm. The larvae enter the soles of the feet and travel the bloodstream to the lungs before settling in the intestine, where sufferers can experience stunted growth, anemia, and exhaustion. More than 40 percent of the population in southern states had hookworm infection in the early 20th century. The Rockefeller Sanitary Commission for the Eradication of Hookworm Disease used Rockefeller’s $1 million donation to map out high-risk areas and made a concentrated effort to cure infected residents with Epsom salts and thymol while educating the public on the need for improved sanitation systems.

While it was thought for decades that hookworm had been essentially eradicated in the United States, a recent study found that it still occurs in impoverished areas of Alabama and possibly other regions of the deep south—but not with the severity of the early 20th century.

6. HE LIKED HANDING OUT DIMES TO STRANGERS.

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In the early 1900s, Rockefeller often traveled by ferry from his home in Tarrytown across the Hudson River and into Nyack, New York. When his ferry docked, he would typically be greeted by children. Rockefeller came prepared, handing out dimes to his welcoming party. Rockefeller was also known to hand out coins to adults. He reportedly did this in part to instill habits of savings and thrift in people. Many of them hung on to their famous “Rockefeller dimes” as a keepsake.

7. SOMEONE PLANNED TO BLOW HIM UP.

At the turn of the century, bomb threats and detonations were often used to make a point against capitalism by radicals looking to upend the system; business barons like J.P. Morgan and Rockefeller were targeted. In the case of Rockefeller, it’s been proposed that he was targeted for his family’s role in the Ludlow Massacre in Colorado, when several striking miners—and even children—were killed during fighting with the Colorado National Guard and mine guards. Fortunately for Rockefeller, his would-be assassins never made it to his Tarrytown home: On July 4, 1914, an explosion went off in a Harlem tenement, killing several anarchists who had been storing dynamite at the location. Their plan had been to leave it at Rockefeller’s doorstep.

8. MARK TWAIN PLAYED A ROLE IN STANDARD OIL'S DOWNFALL.

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In 1900, Ida Tarbell, the daughter of one of Rockefeller's business rivals, decided to even the score with Rockefeller by writing an extensive 19-part expose on his questionable business practices for McClure’s magazine. A key source was Henry Rogers, who worked for Rockefeller as an executive for Standard Oil for roughly 25 years. Rogers heard of the series Tarbell was working on and felt Standard Oil should be involved, asking his friend Mark Twain to inquire with McClure’s. Twain eventually asked, “Would Miss Tarbell see Mr. Rogers?” and a meeting was arranged. Rogers later grew upset when he saw Tarbell’s articles, but it was too late. Her reporting led to a 1911 Supreme Court ruling that broke up Standard Oil for good, mincing it into a series of companies that later became known as Chevron, ExxonMobil, and others. Tarbell didn’t spare words about her vendetta or potential lack of objectivity. In the copy, she referred to the slim Rockefeller as a “living mummy.”