MOSCOW (Reuters) - Alexei Navalny has been the biggest thorn in the Kremlin's side for more than a decade, persistently detailing what he says is high-level graft and mobilising crowds of young protesters in a country where the opposition has no meaningful power.
The 44-year-old lawyer, in a coma in a Berlin hospital after what Germany says was a poisoning with a Soviet Novichok nerve agent, has never challenged President Vladimir Putin at the ballot box but is the highest-profile leader of Russia's deeply divided government opponents.
Part of a new generation prepared to take to the streets to make their views heard, he came to prominence when demonstrations against Putin took off in December 2011, 12 years after the former KGB officer first came to power.
Navalny was one of the first protest leaders arrested and, after 15 days in jail for obstructing police, he emerged a hero, with protesters chanting his name at demonstrations and giving his booming, rousing speeches the biggest cheers.
By the time the protests started to fade in the spring of 2012, Putin was back in the Kremlin as president while Navalny had established himself as the largely undisputed leader of an opposition operating mostly outside official structures.
That pre-eminence has faded amid internal policy differences and squabbling among various factions, and some other opposition figures have questioned how far his support extends beyond Russia's big cities.
He has been repeatedly detained for organising public meetings and rallies and sued over the detailed investigations into corruption which he posts on his YouTube channel, gaining millions of views.
He was barred from running in a presidential election in 2018, and jailed last summer after calling for mass opposition protests in Moscow, which brought tens of thousands of people onto the streets.
His anti-corruption foundation has been found guilty of violating a "foreign agent" law and he was convicted of corruption by Russian authorities in 2013. His supporters say it and other cases against him are politically motivated.
"Putin is very angry and is stamping his feet," he said last year after police raided the homes and offices of his supporters across Russia in what they said was an investigation into money laundering at his foundation.
Four days earlier, he had led a tactical voting campaign that dented the ruling party's hold on Moscow's city assembly.
Navalny was born on June 4, 1976, the son of an army officer, and grew up mainly in Obninsk, about 100 km (60 miles) southwest of Moscow.
After a law degree, he spent time in the United States on a fellowship at Yale, which pro-Kremlin critics have seized on as evidence that he is a foreign agent.
In 2007, he was expelled from Russia's liberal Yabloko opposition party for nationalist views, which he has since toned down.
He also studied securities and exchanges and bought small stakes in some of Russia's biggest companies to demand greater transparency for shareholders and the public.
(Editing by Angus MacSwan and Kevin Liffey)