The Black Hundreds were reactionary, monarchist, and ultra-nationalist groups in Russia in the early 20th century. They were staunch supporters of the House of Romanov, and opposed any retreat from the autocracy of the reigning monarch. Their name arose from the medieval concept of "black", or common (non-noble) people, organized into militias.

The Black Hundreds were noted for extremism and incitement of pogroms, nationalistic Russocentric doctrines, as well as various xenophobic beliefs, including antisemitism, anti-Polish sentiment and anti-Catholic sentiment, as well as sentiment against the Ukrainian secessionism. The Black Hundreds attracted large numbers of members from all Orthodox Eastern Slavic folks (Russians / 'Great Russians', Ukrainians / ‘Little Russians’ or Belarusians / 'White Russians') who subscribed to the ideas of ‘pan-Russian’ Orthodox monarchism. The most frequent Jewish pogroms involving members of the Black Hundreds took place in the governments of the Jewish ‘Pale of Settlement’, where the Ukrainian and the Cossack population predominated (a group which, both culturally and ethnically, stood between the ‘Great’ and ‘Little’ Russians).

The ideology of the movement is based on a slogan formulated by Count Sergey Uvarov: "Orthodoxy, Autocracy, and Nationality".

The term was intended to be pejorative in revolutionary newspapers, but adherents used it in their own literature. They traced the term back to the "black lands", where peasants, merchants, and craftsmen paid taxes to the government (compare to Black council), meanwhile lands owned by the nobility and church were called "white lands"; the term "hundred" (sotnya) was used to refer to a feudal administrative division. In the right wing extremist imagination, it was the loyal people of the Black Hundreds who gathered to fight Poles and traitors when it was needed.

Revolutionary newspapers identified the Black Hundreds as a threat, describing them as "hooligan gangs" paid by the government to threaten political opponents. The Menshevik leader Julius Martov feared that the government would bribe lower class individuals to act against the social revolutionaries of the time. The term "Black Hundreds" started to appear in newspapers around 1905, along with warnings that the government would mobilize the Black Hundreds in pursuit of mass murder, and would even resort to inciting anti-Jewish pogroms and strife between different religious groups. They alleged that the Black Hundreds were being organized by the police, and called for resistance. The term became more closely associated with pogrom-like violence after thousands of people were killed in attacks on demonstrations, public assemblies, and in the antisemitic pogroms that followed the October Manifesto.

A number of Black Hundred organizations formed during and after the Russian Revolution of 1905, such as:

and others.

In 1905-1914 Black Hundreds didn't exist as a single movement; numerous political groups and parties representing monarchist ideology in the Russian Empire had different ideological views. Even the concept of "Russian nation" was interpreted differently, with some seeing "Russian-ness" as a religious category, while others defined it in a civic or ethnic sense, or as their combination.