Union of the Russian People
The Union of the Russian People (URP) was the most important of the Black Hundreds right-wing monarchist and nationalist political organizations in the Russian Empire between 1905 and 1917. It was a leading advocate of Pan-Slavism.
Leftist Wikipedia makes various questionable claims regarding the organization, such as that its most important characteristic was anti-Semitism and that it was an early example of fascism (broad sense).