Who is Russian oligarch Roman Abramovich?

Chelsea Football Club owner Roman Abramovich looks on from the stands during the Barclays Premier League match between Chelsea and Manchester City at Stamford Bridge stadium in London on April 16, 2016. (Paul Gilham/Getty Images)

Among soccer fans, Roman Abramovich is a household name. As the longtime owner of the English Premier League’s Chelsea Football Club, the 55-year-old Russian businessman has transformed the association into a global powerhouse.

At the same time, Abramovich has worked to stay out of the spotlight, rarely giving interviews or posing for photos. In March, that posture was largely upended, as Western governments targeted Abramovich and other Russian oligarchs to punish Moscow for its invasion of Ukraine.

On Tuesday, the silver-haired billionaire was spotted in Istanbul on the sidelines of peace negotiations between Russia and Ukraine, although his exact role in the talks remains unclear. Also this week, an associate of Abramovich’s said that he and other negotiators had fallen ill of suspected poisoning after a meeting in early March.

What is an oligarch, really?