Unicorns are some of the most famous mythical creatures, often depicted as white horses each with a spiraling horn erupting from its forehead. It's said that unicorns tend to live in forests, and are rarely seen by humans. Unicorns are also private companies or startups with valuations over $1 billion. The term was first coined by venture capitalist Aileen Lee in 2013. Some popular unicorns include SpaceX, Robinhood, and Instacart.