Tesla Motors
Tesla Motors was founded on July 1, 2003, by Martin Eberhard and Marc Tarpenning. It is important that you know this because many believe Elon Musk came up with the Tesla name and somehow founded the company.
What actually happened was that Tesla Motors sought out funding to develop their first electric vehicle. It is common for companies to seek out venture capital/investments in their company like this. However, the two men lucked out because Elon Musk happened to come into a lot of money a little before this.
That led to his $6.4 million investment in Tesla Motors in February 2004. This was quite a lot of money for a newer company and Musk was not about investing and getting his money back plus interest. Rather, he wanted his investment to lead to an ownership stake.
His investment made him the largest shareholder, but he was not part of the major corporate structure until 2008 when he became the CEO. A later lawsuit involving Tesla Motors in 2009 led to Musk being allowed to call himself a co-founder of the company. This is crazy, considering he clearly was not a founder and simply invested at the right time.