Elon Reeve Musk (/ˈiːlɒn/ EE-lon; born June 28, 1971) is a businessman known for his leadership of Tesla, SpaceX, and X (formerly Twitter). Since 2025, he has been a senior advisor to United States president Donald Trump and the de facto head of the Department of Government Efficiency (DOGE). Musk has been considered the wealthiest person in the world since 2021; as of March 2025, Forbesestimates his net worth to be US$345 billion. He was named Time magazine’s Person of the Year in 2021.