Alexei Anatolyevich Navalny (Russian: Алексей Анатольевич Навальный, IPA: [ɐlʲɪkˈsʲej ɐnɐˈtolʲjɪvʲɪtɕ nɐˈvalʲnɨj]; 4 June 1976 – 16 February 2024) was a Russian opposition leader, anti-corruption activist and political prisoner. He founded the Anti-Corruption Foundation (FBK) in 2011. He was recognised by Amnesty International as a prisoner of conscience and was awarded the Sakharov Prize for his work on human rights.

Through his social media accounts, Navalny and his team published material about corruption in Russia, organised political demonstrations and promoted his campaigns. In a 2011 interview, he described Russia's ruling party—United Russia—as a "party of crooks and thieves", which became a popular byname. Navalny and the FBK have published investigations detailing alleged corruption by high-ranking Russian officials and their associates.

Navalny twice received a suspended sentence for embezzlement, in 2013 and 2014. Both criminal cases have been widely considered politically motivated and intended to bar him from running in future elections. He ran in the 2013 Moscow mayoral election and came in second with 27.2% of the vote, but was barred from running in the 2018 presidential election.

In August 2020, Navalny was hospitalised after being severely poisoned with a Novichok nerve agent.