Russian tycoon Boris Berezovsky has been found dead at his home in Surrey.
It is not known how the 67-year-old - a wanted man in Russia - died.
He had survived numerous assassination attempts, including a bomb that decapitated his chauffeur.
Mr Berezovsky, a former Kremlin power broker, saw his fortunes decline when Vladimir Putin became Russian president. Mr Berezovsky had lived in the UK since 2000.
Last year, he lost a case against fellow Russian businessman and Chelsea Football Club owner Roman Abramovich in which he claimed he was intimidated into selling shares in Russian oil giant Sibneft.
Mr Berezovsky had been claiming £3bn ($4.7bn) in damages.
But ruling in Mr Abramovich's favour, the London Commercial Court judge said Mr Berozovsky had been an "inherently unreliable" witness.