MOSCOW, March 23 - From car salesman to Kremlin king-maker to billionaire political exile, Boris Berezovsky seemed to play a role in nearly every crucial scene in the roller coaster drama of post-Soviet Russia.
A mathematician by training, Berezovsky's expertise at political calculus gave him power beyond his position in a career that made him many enemies - the most prominent of them Vladimir Putin, the man he helped bring to power.
In a country with a rich history of court intrigue and a reputation for opacity in the Kremlin from tsarist, his maneuvering earned him comparison to Russia's ultimate behind-the-scenes operator, the "mad monk" Grigory Rasputin.
Credited with a part in saving Boris Yeltsin's political skin and shaping Putin into presidential material with the help of money and media, he was then blamed - formally or not - for dark episodes that followed his falling out with the Kremlin.
Berezovsky traded unofficial accusations with Russian authorities over killings such as the polonium poisoning death of Alexander Litvinenko in London in 2006, and survived assassination attempts himself.
In 1994, Berezovsky's car was blown up and his driver killed - reportedly decapitated. In 2007, he said British police had warned him of a plot to kill him.
His death at age 67 may only begin the latest mystery. British police said it was "unexplained."
Berezovsky was born in Moscow on January 23, 1946. After graduating from the Moscow Institute of Timber Technology in 1967, he earned an advanced degree in physics and mathematics and membership in the prestigious Academy of Sciences.
A fierce opponent of communism, Berezovsky made his name selling cars and rose in the 1990s to control a vast financial empire based around the LogoVAZ industrial giant, which had its roots in the auto sales business.
As a friend of President Boris Yeltsin's family, a financier of his 1996 re-election campaign and a board member of a main TV network, he helped Yeltsin overcome ill-health and a Communist challenge to win a new term.
Communist Party leader Gennady Zyuganov later compared Berezovsky to Rasputin, the wild-eyed monk and mystic who wielded influence over the family of the last Russian tsar, Nicholas II.
Rewarded with a seat on Yeltsin's national Security Council, he helped implement the peace deal that ended Russia's first war with rebels in the Chechnya region and was a go-between in talks to free hostages there.
Many - not least Berezovsky - say he played a key role in plucking Putin out of obscurity and engineering Yeltsin's appointment of the former KGB officer as acting president when he stepped down abruptly on the last day of 1999.
"He presented (Putin) to the Russian establishment of that time, brought him into Boris Yeltsin's close circle, and he was the first to believe that out of this indistinct bureaucrat, a successor could be made," commentator Sergei Parkhomenko said.
But Berezovsky fell foul of the Kremlin early in Putin's first term and moved to Britain, where he was given asylum.
Sheltered from criminal cases in which he has been sentenced to years in prison in absentia, and which he has dismissed as politically motivated, he harried Putin for a decade from London. He teamed up with other exiles to implicate the Russian state in killings and rights abuses.
Russian authorities have rejected those claims as bids to blacken Russia's reputation and tried to turn the tables, with officials and state media casting him as an almost clownishly villainous figure responsible for some of the same crimes himself.
Berezovsky's fortunes fell when he lost a $6 billion legal battle last year with Chelsea Football Club owner Roman Abramovich, a former protege he accused of using the threat of Kremlin retribution to scare him into selling assets cheaply.
"After the loss in court ... he was in deep depression," said Alexei Venediktov, editor of Russia's Ekho Moskvy radio.
"I think it was probably his health, including depression, and his age," Venediktov said of his death. "Boris Abramovich never took it easy - he was a fighter, he led an active lifestyle, and unfortunately he has left life in this way."
Berezovsky leaves a deeply mixed reputation. Many Russians, Venediktov said, "see Boris Abramovich as a mythological figure -- as Heracles or, on the contrary, as Hades."
(Additional reporting by Megan Davies; Editing by Stephen Powell)