Russian President Vladimir Putin has overseen a ruthless crackdown on dissidents and critics during his 24 years in power, and all his major domestic opponents are now dead, exiled or in prison.

His staunchest critic of the last decade, Alexei Navalny, died last month in an Arctic prison colony.

Thousands turned out to mourn him at his funeral in Moscow, some voicing rare dissent in the streets of the capital.

His widow Yulia Navalnaya has taken up his cause and urged supporters to protest on Sunday -- the third day of an election that is expected to hand Putin another six-year term.

Dozens more critics of the Kremlin and war in Ukraine remain behind bars.

Opponents and critics

Opposition politician Vladimir Kara-Murza, 42, was jailed last April for 25 years, the harshest sentence so far for speaking out against the war.

He was charged with "treason" after using a speech in the United States to say Russia had committed "war crimes" against Ukraine.

Kara-Murza, who is also a British citizen, suffers from serious health problems which his lawyers say were due to two poisoning attempts orchestrated by Russia's FSB security service in 2015 and 2017.

Following Navalny's death, calls have grown to release him.

Jailed opposition politician Ilya Yashin, 40, was among those to raise concern.

A close ally of both Boris Nemtstov — the opposition politician shot dead in 2015 — and Navalny, Yashin was sentenced to eight-and-a-half years in prison in December 2022. 

He had criticised Moscow's invasion of its neighbour and discussed Russian atrocities in Bucha, Ukraine, where Kyiv says more than 400 civilians were killed and tortured.

In messages passed through his lawyers from behind bars, he has called out Russian "war crimes" and said Putin has "gone mad".

Two other Navalny allies — Lilia Chanysheva and Ksenia Fadeyeva — are serving seven-and-a-half and nine-year sentences for "extremism."

The two women headed regional branches of Navalny's organisation and fell victim to the Kremlin's drive to punish his supporters.

Russian authorities also locked up nationalist pro-war critic Igor Girkin, 53, for four years.

He spent months railing against Russia's military leaders for not prosecuting the war in Ukraine more aggressively.

Girkin had commanded pro-Moscow rebels in eastern Ukraine in 2014, and was planning to run against Putin in the presidential election.

Advocates and pacifists

Dozens of human rights advocates and anti-war voices have also found themselves in the Russian authorities' crosshairs.

A court sentenced veteran rights campaigner Oleg Orlov last month to two-and-a-half years in prison for denouncing the military offensive.

Orlov, 70, a key figure in the Nobel Prize-winning Memorial group, was punished over an article in which he said Russia had turned into a "fascist" state.

His Memorial human rights group says there are more than 250 political prisoners in Russian jails.

They include pro-peace artist Alexander Skochilenko, who was sentenced to seven years for spreading "false information" about the army when she replaced supermarket price tags with anti-war slogans.

Exiles

Threatened with the prospect of prison at home, other opposition figures have left Russia for countries where they are more able to speak freely without fear of arrest.

The Kremlin has painted them as Western-funded puppets and some have struggled to remain relevant.

Former oil tycoon Mikhail Khodorkovsky, 60, has run anti-Putin organisations and bankrolled opposition groups from London since being released from a decade-long spell in a Russian prison in 2013.

He had been targeted with controversial fraud charges widely seen as retribution for supporting democratic initiatives in Russia and speaking out publicly against Putin during the early years of his rule.

Once seen as an opposition leader and fierce rival, his influence has waned in exile.

A host of Navalny allies, led by his widow, Yulia Navalnaya, are also campaigning from exile. 

They include his ex-chief of staff Leonid Volkov; Ivan Zhdanov, who led the now-outlawed Anti-Corruption Foundation in Russia; and Maria Pevchikh, Navalny's main investigator and chair of his international organisation.

Kremlin critic and chess legend Garry Kasparov — who has called Russia "fascist" -- has lived in the United States for more than a decade, heading various international foundations and human rights initiatives.

Several former Russian lawmakers, such as father-and-son duo Gennady and Dmitry Gudkov, have also fled in the face of arrest. 

Like Putin, Gennady Gudkov, 67, was a former KGB agent turned politician. He initially backed Putin in parliament before moving to oppose the Kremlin and being expelled in 2012.

Ilya Ponomarev, 48, was the only member of Russia's parliament to vote against the annexation of Crimea from Ukraine in 2014. 

Charged with embezzlement shortly after, he went into exile and obtained Ukrainian citizenship.

He now heads the political wing of the Freedom of Russia Legion, an underground resistance group and militia that has claimed responsibility for attacks inside Russia.