The government reforms imposed by Tsar Alexander II of Russia, often called the Great Reforms (Russian: Великие реформы, romanized: Velikie reformy) by historians, were a series of major social, political, legal and governmental reforms in the Russian Empire carried out in the 1860s.

By far the most important was the emancipation reform of 1861 which freed the 23 million serfs from an inferior legal and social status, and helped them buy farmland. Many other reforms took place, including the:

By 1865 reaction began, and some reforms were cut back. After the tsar's assassination in 1881, his successor Alexander III reversed many reforms.

The Russian Empire in the 19th century was characterized by very conservative and reactionary policies issued by the autocratic tsars. The great exception came during the reign of Alexander II (1855–1881), especially the 1860s. By far the greatest and most unexpected was the abolition of serfdom, which affected 23 million of the Empire's population of 74 million. They belonged to the state, to monasteries and to 104,000 rich gentry landowners—it was the last group that was emancipated first.

As soon as he became tsar Alexander set up numerous commissions that studied various proposals for reforms in practically every area. Experts debated in draft of the proposals, but Alexander made all the final decisions.

While the emancipation of the serfs in 1861 was the most famous and dramatic reform, a host of new reforms affected diverse areas. The tsar appointed Dmitry Milyutin to carry out significant reforms in the Russian armed forces. Further important changes were made concerning industry and commerce, and the new freedom thus afforded produced a large number of limited liability companies. Plans were formed for building a great network of railways, partly to develop the natural resources of the country, and partly to increase its power for defense and attack.

A new judicial administration (1864), based on the French model, introduced security of tenure. A new penal code and a greatly simplified system of civil and criminal procedure also came into operation. Reorganisation of the judiciary occurred to include trial in open court, with judges appointed for life, a jury system and the creation of justices of the peace to deal with minor offences at local level. Legal historian Sir Henry Maine credited Alexander II with the first great attempt since the time of Grotius to codify and humanise the usages of war.

When Alexander II ascended the throne in 1855, the largely peasant conscripted army in the Crimean War was a national disgrace, and clearly demonstrated that despite its large size, the Russian army was no longer competitive to smaller industrial powers such as Britain and France. The demand for reform was widespread, but unorganized. There had been little consideration of how the complex economic, social, political, and legal roles of the service would be ended. The Tsar decided to abolish serfdom from above, setting up a new system whereby the state would be able to purchase farmland from the landowners and sell it to the freed serfs. The Tsar told Moscow nobles: "Better that the reform should come from above than wait until serfdom is abolished from below." Historians have debated Alexander's role. Soviet-era historians downplayed him, as they believed social forces caused history not individuals. Non-Marxist critics say he did not go far enough, especially since he rejected any parliament or duma.