Editor's Note: Inc. Magazine announced its pick for Company of the Year on Monday, November 23. It's Slack! See which one Inc. readers chose as their favorite company of 2015. Here, we spotlight Elon Musk, one of the contenders for the title in 2015.

When Elon Musk was named Inc.'s Entrepreneur of the Year back in 2007, he was a fresh-faced 36-year-old still best known to the general public as the co-founder and former CEO of PayPal. SpaceX had launched two rockets; Tesla had sold a total of 600 cars.

Musk's ambitions were huge, though, and it was clear he had the brains and capital to make them a reality. And while one can argue he's deserved the award practically every year since, in 2015, Musk went downright nuclear. Not only did his name become a verb, but his status vaulted from star entrepreneur to legend as well.

That 2007 cover proclaimed that Musk was "building the coolest car ever." It seems he's succeeded: This spring, Tesla introduced the Model S 70D, which was almost immediately named Car and Driver's "car of the century." The dual-motor electric, four-wheel-drive vehicle can travel 240 miles on a single charge and runs $75,000, reasonable among its competitors.

Even more important was what Musk did next: He announced the smaller, less expensive Model 3. At $35,000, it holds the potential to make electric cars as accessible as the Model T made internal-combustion cars in its day.

Then there's SpaceX, which Musk founded in 2002 with the stated long-term goal of sending humans to Mars. The company is about to break ground on its commercial launch pad--the first ever in the United States--in Brownsville, Texas. While it lost a Falcon 9 rocket to an explosion back in June, SpaceX is moving closer to significantly slicing the cost of space exploration by launching and landing a fully reusable rocket. And this spring, Musk asked the Federal Communications Commission for permission to build a system of satellites that will beam the Internet to even the most remote corners of the earth.

But what made the biggest splash in 2015 was Tesla's Powerwall battery, announced during a much-hyped presentation back in April. About the size of a suitcase, the wall-mounted lithium-ion battery stores excess energy from the power grid or from solar panels (a logical fit with another Musk venture, SolarCity), allowing homeowners to use the excess at night or on cloudy days. And the larger Powerpack battery can be used by commercial buildings--or by utility companies in lieu of highly polluting power plants.

"Our goal is to fundamentally change the way the world uses energy," Musk said at the Powerwall's April unveiling in Hawthorne, California. So far, the batteries, which start at $3,500, are sold out through 2016. Production has moved to Tesla's massive, still-unfinished Nevada-based Gigafactory, and the company has racked up $1 billion in sales--around 100,000 orders--since May. Tesla estimates it can do $450 million per quarter after next year, at which point Musk hopes the company can reach profitability.

It would take two billion Powerpack batteries to power the entire world, Musk says. A huge number, yes, but as Musk has pointed out, it's not unheard of for a large product to be so widely scaled--that's about how many vehicles are currently on the world's roads. If the price point comes down--some expect it'll drop by about 50 percent in the next few years--Tesla could truly be on the verge of turning the energy industry upside down.

How does one person achieve all this? 2015 was also the year we learned more about Musk the person, for better or worse. Among the revelations in his biography, released in May: He wishes his body didn't require him to waste time eating food; he hates vacations; he believes our society is "soft" because not enough people are working on Saturdays.

At this point, Musk has become a caricature of entrepreneurship, with his absurd attention to productivity and a lack of empathy for those seeking work-life balance. That's somewhat ironic, given that each of his companies has the potential to improve people's lives. And not to defend ruthless leadership tactics, but raise your hand if you think Tesla would be where it is without an insanely driven leader at its helm.