Mikhail Fridman

Mikhail Fridman, cofounder of Alfa Bank, Russia's largest non-state bank, was hit with sanctions after Russia invaded Ukraine.

Soon after, Fridman (who also has Israeli citizenship) stepped down from his Luxembourg holding company, LetterOne, and reduced his shareholding.

Fridman's properties in London, including the $100 million Victorian-era Athlone House estate where he mostly lived, have been frozen by the U.K.

A Ukraine native, Fridman and his college buddies German Khan and Alexei Kuzmichev started commodities trader Alfa-Eco in 1989.

Thanks to Kremlin connections (one of his employees who later served as Putin's chief political advisor) he acquired additional assets in telecom, banking and oil.

In 2013 he made $5.1 billion in cash when the trio and partners sold stakes in oil giant TNK-BP for $14 billion.