Lee Sedol (Seo Myung-gon/Yonhap/Reuters)
Lee Sedol is a lifelong Go player and 18-time world champion at the game.
Lee, the fifth youngest player to go professional in South Korea at 12 years old, is a legendary figure in the Go world.
In 2016, he played a series of high profile matches against AlphaGo, an AI developed by Google DeepMind. Despite winning one match, Lee ultimately lost 1-4.
Before the famous 2016 AlphaGo tournament, Lee said he'd retire to promote the game in the United States. Lee officially announced his retirement years later, in November, 2019, though he plans to play against HanDol, another AI agent, in January, 2020.
If you want to see where human-machine competition is fiercest, look to games. Complex, rules-based games present the ideal environment to train AI systems, where the industry's top startups compete against the world's best players.