The Decembrist Revolt (Russian: Восстание декабристов, romanized: Vosstaniye dekabristov, lit. 'Uprising of the Decembrists') took place in Russia on 26 December [O.S. 14 December] 1825, following the sudden death of Emperor Alexander I.

Alexander's heir-presumptive, Konstantin, had privately declined the succession, unknown to the court, and his younger brother Nicholas ascended the throne as Emperor Nicholas I. While some of the army had sworn loyalty to Nicholas, a force of about 3,000 troops tried to mount a military coup in favour of Konstantin. The rebels, although weakened by dissension between their leaders, confronted the loyalists outside the Senate building in the presence of a large crowd. In the confusion, the Emperor's envoy, Mikhail Miloradovich, was assassinated. Eventually, the loyalists opened fire with heavy artillery, which scattered the rebels. Many were sentenced to hanging, prison, or exile to Siberia. The conspirators became known as the Decembrists (Russian: декабристы, romanized: dekabristy).