The Russian Revolution of 1905, also known as the First Russian Revolution, was a revolution in the Russian Empire which began on 22 January 1905 and led to the establishment of a constitutional monarchy under the Russian Constitution of 1906, the country's first. The revolution was characterized by mass political and social unrest including worker strikes, peasant revolts, and military mutinies directed against Tsar Nicholas II and the autocracy, who were forced to establish the State Duma legislative assembly and grant certain rights, though both were later undermined.

In the years leading up to the revolution, impoverished peasants had become increasingly angered by repression from their landlords and the continuation of semi-feudal relations. Further discontent grew due to mounting Russian losses in the Russo-Japanese War, poor conditions for workers, and urban unemployment. On 22 January [O.S. 9 January] 1905, known as "Bloody Sunday," a peaceful procession of workers, led by Georgy Gapon, was fired on by guards outside the tsar's Winter Palace in Saint Petersburg. Widespread demonstrations and traditional strikes spread all over the empire and were brutally repressed by the tsar's troops. In June, sailors on the battleship Potemkin undertook a mutiny, and in October, a strike by railway workers turned into a general strike in Saint Petersburg and Moscow. The striking urban workers established councils, including the inaugural St. Petersburg Soviet of Workers' Deputies, in order to debate their course of action. The influence of revolutionary parties, in particular the Socialist Revolutionary Party and Russian Social Democratic Labor Party, quickly escalated. At the same time, the reactionary pro-monarchist Black Hundreds began attacks on intellectuals, revolutionaries, and the Jewish population.

In response, the tsar issued the "October Manifesto," a pledge to create a legislative assembly, halt censorship and violations of freedom of association, and expand the right to vote. The constitution, drafted by Sergei Witte and enacted on 6 May [O.S. 23 April] 1906, did not bring an end to the turmoil, as anti-monarchist revolutionaries continued to rally for a constituent assembly. The movement for reform fragmented into conservative Octobrist and liberal Kadet factions, and the left split into moderates content with the reforms and those who desired a full overthrow of the tsar. The revolution slowly fizzled out in the face of harsh repression as troops returned after the end of the Russo-Japanese War in September 1905. Despite popular participation, the Duma was unable to issue laws of its own and often came into conflict with the tsar, who in July 1906 dissolved the first Duma and appointed Pyotr Stolypin as prime minister, who set about restoring autocratic rule. In June 1907, the second Duma was dissolved and an electoral reform which favored the propertied classes was decreed.

Many historians contend that the Revolution of 1905 set the stage for the Russian Revolution of 1917, which saw the monarchy abolished, the tsar executed, and a socialist state established. Calls for the peasantry and workers to take power by force were present in the 1905 revolution, but many of the revolutionaries who were in a potential position to lead were either in exile or in prison while it took place. Vladimir Lenin later famously described the Revolution of 1905 as the "dress rehearsal" without which the "victory of the October Revolution in 1917 would have been impossible."

Because the Russian economy was tied to European finances, the contraction of Western money markets in 1899–1900 plunged Russian industry into a deep and prolonged crisis; it outlasted the dip in European industrial production. This setback aggravated social unrest during the five years preceding the Revolution of 1905.

The Tsarist government did recognise some of these problems, albeit shortsightedly. The Minister of the Interior Vyacheslav von Plehve had said in 1903 that, after the agrarian problem, the most serious issues plaguing the country were those of the Jews, the schools, and the workers, in that order.

Any residual popular loyalty to Tsar Nicholas II was lost on 22 January 1905, when his soldiers fired upon a crowd of protesting workers, led by Georgy Gapon, who were marching to present a petition at the Winter Palace.

Every year, thousands of nobles in debt mortgaged their estates to the noble land bank or sold them to municipalities, merchants, or peasants. By the time of the revolution, the nobility had sold off one-third of its land and mortgaged another third. The peasants had been freed by the emancipation reform of 1861, but their lives were generally quite limited. The government hoped to develop the peasants as a politically conservative, land-holding class by enacting laws to enable them to buy land from nobility by paying small installments over many decades.