Vladimir Putin is due to be sworn in for a fourth term as president of Russia on Monday after winning the last election in March.
He has been in power for 18 years, whether as president or prime minister, and opponents have likened his tenure to the reign of a tsar, or emperor.
Riot police confronted protesters against his rule in Moscow and other Russian cities on Saturday.
There have been fears of new unrest on Monday as he takes office.
The inauguration at the Kremlin in Moscow is likely to be lower-key than in 2012, AFP news agency reports.
Mr Putin is only expected to meet volunteers who took part in his election campaign, the agency says.
Why were there protests?
More than 1,000 arrests are said to have been made in 19 cities across Russia on Saturday, nearly half of them in Moscow.
Mr Putin was re-elected president with more than 76% of the vote, his best ever election performance, but widespread irregularities were reported by some international observers. Allegations of ballot-rigging had dogged previous elections too.
The country's best-known opposition leader, Alexei Navalny, was barred from standing against Mr Putin, on grounds of a conviction for embezzlement which he denies and alleges was politically motivated.
Mr Navalny was arrested briefly as he tried to join Saturday's unauthorised protest rally in Moscow under the slogan "He's not our tsar".
Domestic opponents accuse Mr Putin of undermining democracy in Russia - a policy dubbed "managed democracy" - to keep genuine opposition parties out of parliament and ensure that he and his allies retain power indefinitely.
Could Putin just go on and on?
First elected president in 2000, Mr Putin renewed his four-year term in 2004 before stepping aside in 2008 to serve as prime minister under his protege, Dmitry Medvedev, because by law he could only serve two consecutive terms.
Few doubted who was really in charge and in 2012 Mr Putin returned as president, this time for a term of six years.
If and when he reaches the end of his fourth term in 2024, the 65-year-old will have been in power for nearly a quarter of a century.
That would still fall short of Soviet dictator Joseph Stalin's 31 years in power or, indeed, the reigns of some Russian tsars such as Alexander II (26 years) and Nicholas I (30 years).
Spy turned president
1952: Born 7 October in Leningrad (now St Petersburg), Russia's second city, studies law and joins KGB secret police, serving as spy in communist East Germany
1990s: After serving as top aide to mayor of St Petersburg, enters Boris Yeltsin's Kremlin in 1997, where he is made chief of the FSB (the KGB's successor)
1999: Appointed prime minister, becomes acting president upon Yeltsin's resignation
2000: Elected president and serves two four-year terms
2008: Barred from running for a third consecutive term, stuns analysts by returning to post of prime minister while his protege Dmitry Medvedev becomes president
2012: Re-elected president and for term of six years, under new law
2018: Re-elected for fourth term
How has Russia changed under Putin?
Ordinary Russians welcomed the stability associated with Mr Putin's early years in office when inflation was reined in and basic state functions like the welfare system were shored up.
Separatist violence in the North Caucasus which had plagued the administration of Mr Putin's predecessor, the late Boris Yeltsin, was finally brought to a bloody end.
As prosperity grew, fuelled by oil and gas revenue, Mr Putin oversaw an increase in state power, rolling back independent media as well as political freedoms.
His decision to annex Crimea from Ukraine in 2014 sparked one of the biggest international crises since the Cold War, incurring Western sanctions which continue to this day.
Russia's alleged interference in the 2016 US presidential election soured international relations even further, while this year saw Mr Putin accused by the UK of responsibility for a nerve agent attack on its soil - allegations denied by Moscow.
Political analyst Dmitry Oreshkin told AFP Mr Putin's approach to the international community would have to change over his new term.
"Russia hasn't been so isolated since the Soviet war in Afghanistan," he said.
"Now his [Putin's] task isn't to bring any new lands to Russia but to force the world to consider Russia's interests and accept its previous conquests," Oreshkin added.
