Elon Musk has become the richest person in the world, replacing Amazon founder Jeff Bezos at the top of the rich list.
He is thought to be worth more than $185 billion - which is equivalent to £166 billion.
Musk is best known for owning a car company called Tesla and a commercial space flight business called Space X .
Tesla is one of the most successful car companies in the world.
The value of Tesla has increased a lot in the past year. It's worth almost $700 billion, which is equivalent to £516 billion.
To put that figure in perspective, it means the company is worth more than car manufacturers Toyota, Volkswagen, Hyundai, GM and Ford put together.
As Tesla's value has gone up, so too has the personal wealth of its founder Elon Musk.
He reacted to the news on social media by saying: "How strange."
Don't feel too sorry for the previous holder of the world's richest person, though.
Jeff Bezos, who made his fortune as the founder of online shopping website Amazon, is only just behind Musk on the rich list with a value of $184 billion.
Born in South Africa, the young Elon had a tough time growing up and was bullied. But that didn't stop him from dreaming of success.
As a boy Elon was a keen reader and learnt how to code computers. He even made his own video game called Blastar.
Later he moved to Canada and then the United States setting up his first company with his brother Kimbal in 1995 which he later sold to create a company called X.com.
X.com became PayPal, a website that allows you to pay for things online which is used by adults all over the world.
Elon Musk sold PayPal for $1.5billion, and received personally received $165million from its sale.
With that $165million Elon Musk looked to the stars and created another new company called Space X. It's long term plan was to help people live on other planets.
In 2004 he helped set up the electric car company Tesla. In the 16 years that have followed the company has had major ups and downs, losing billions of dollars.
You can read more about Musk's business ventures here.