Oleg Deripaska owns the world's biggest aluminium producer.
Oleg Deripaska - a Russian billionaire who has had contacts with senior UK politicians - is one of a group of businessmen who became fabulously wealthy after the break-up of the Soviet Union.
Known as "oligarchs", these entrepreneurs gained control over Russia's vast oil, gas and mineral wealth, as the Soviet Union, under Presidents Gorbachev and Yeltsin, opened its economy.
With fortune estimated at $28bn (£16bn) by Forbes Magazine, Mr Deripaska is believed to be Russia's richest man.
And as the sole owner of investment company Basic Element, he has interests in the metals, energy, manufacturing and aviation industries.
Basic Element owns the world's biggest producer of aluminium, UC Rusal - and Mr Deripaska is sometimes referred to as the "aluminium king".
He started off as a metals trader in the fledgling Russian metals market in 1992.
Between 1993 and 1994 he bought a 20% stake in a Siberian aluminium factory. It was a start that led him to much larger industrial acquisitions.
He has a home in London and was reported at one time to be interested in buying the Premiership football club, Arsenal.
At 40-year-old, Mr Deripaska is one of the youngest of Russia's oligarchs. He is a grandson by marriage to the late Boris Yeltsin, and is married to the daughter of the former Soviet president's last chief of staff.
Unlike some other oligarchs, Mr Deripaska has cultivated a public image of a reserved family man, uncomfortable with ostentatious displays of wealth.
A number of his former associates have brought civil suits against him in the United States, Europe and Russia.
To date, none have succeeded, but that has not prevented the US state department banning Mr Deripaska from entering America, over what it will only refer to as "concerns".