Elon Musk, CEO of Tesla and SpaceX, has previously mentioned owning Bitcoin, Ethereum, and Dogecoin.
1. Bitcoin: Musk has been a public supporter of Bitcoin for some time. In early 2021, he announced that Tesla had invested $1.5 billion in Bitcoin, making Tesla the largest corporate holder of the cryptocurrency.
2. Ethereum: While Musk hasn't spoken extensively about Ethereum, he has shown interest in Ethereum's technology, particularly its smart contract functionality.
3. Dogecoin: Musk has been an outspoken supporter of Dogecoin, a meme-inspired cryptocurrency. He has tweeted about it on multiple occasions and even jokingly referred to it as the future reserve currency.
However, it should be noted that this information is current until February 2024 and may have changed since then.