Elon Musk took on another role, becoming Trump's efficiency boss. Here's the full list of his jobs.

"Together, these two wonderful Americans will pave the way for my Administration to dismantle the Government Bureaucracy," Trump said in an announcement of Musk's new role, which he will carry out alongside entrepreneur Vivek Ramaswamy, who briefly ran against Trump in the Republican race.

Trump added that the pair will work to "slash excess regulations, cut wasteful expenditures, and restructure Federal Agencies."

He likened the DOGE — whose acronym is a seeming nod to Dogecoin, Musk's favorite cryptocurrency — to the Manhattan Project, the program during World War II to create the first nuclear weapons.

The unofficial government department "will provide advice and guidance from outside of Government, and will partner with the White House and Office of Management & Budget to drive large scale structural reform," a statement announcing the creation of the office said.

It will also seek to "create an entrepreneurial approach to Government never seen before," though exactly how it will function remains unclear.

Musk is arguably best known as the CEO of Tesla, which he was an early investor in, and has since gone on to build into a major force in the auto industry. Telsa is one of only a handful of American corporations that have reached a $1 trillion market cap, joining the likes of Apple and Nvidia.

According to the Bloomberg Billionaires Index, the world's richest person saw his wealth boosted to $335 billion on Monday after Tesla stock jumped 9%. Investors have poured into the automaker in the past week, expecting it to benefit from a Trump win after Musk established close ties with him.

Tesla produces and sells a number of electric vehicle models — including Model S, Model 3, Model X, and Model Y — and solar energy storage and generation products.

The billionaire is the boss of SpaceX, the aerospace firm he founded in 2002. With a valuation of around $210 billion, per Forbes

As well as being CEO, Musk is also its chief technology officer and chair.

Musk and his company aim to build a rocket system that will make it possible to build a city on Mars. He hopes one million people will inhabit the red planet by 2050.

A space-friendly Trump could simplify this dream. Experts previously told Business Insider it is highly probable that Musk will be able to influence space policy.

In 2022, the business mogul acquired Twitter for $44 billion, later renaming the social media platform X and scrapping the bird logo. While CEO Linda Yaccarino runs X's daily operations, Musk remains heavily involved.

"The reason I acquired Twitter is because it is important to the future of civilization to have a common digital town square," he said in a note sent to Twitter advertisers.

Changes Musk has made to the service include reinstating accounts formerly banned, like those of Donald Trump and Andrew Tate, extending verification to members that have an X Premium plan, and making likes private.

While Tesla and X are household names, Musk is also involved in less-known companies, like Neuralink, which he cofounded and remains CEO of.

The firm is developing two devices: A brain chip to help treat neurological conditions and a surgical robot which would insert the equipment into the patient.

In January, Musk said the brain implant had been tested for the first time on a human. In August, it was revealed that a second patient received the chip, which he used to play video games and create 3D objects.

Another startup led by Musk is xAI, which, according to the Wall Street Journal, is in talks to raise funding to at a $40 billion valuation. If successful, that would make its worth more than four times the value of X, per Fidelity filings.

In October, xAI reportedly moved into OpenAI's old headquarters in San Francisco. The two cofounded OpenAI in 2015, where Sam Altman is now boss, but Musk stepped down from the board of directors three years later.

Now, the pair lead rival AI firms.