There is no such unified term regarding Russian excesses during colonization as Spanish Black Legend. Definitely, there was a lot of cruelty during Russian conquests, particularly, the massacre of Novgorod (which was not a colonial war though as Novgorod was located in Europe and was an advanced city-state at the time). There was a lot of cruelty against the Chinese in the Far East, in the Caucasus, Central Asia, during conquest of Kazan and Siberia, etc.
If you want a thing that is politically similar to the Black Legend accusations, that is demonizing Russia, the most of accusations against Russia are centered around Stalin's time and early Soviet times. These include
Accusations of cruel repressions against some ethnicities during WWII (Tatars, Chechens, Baltic peoples).
Accusations of war crimes, such as rapes, marauding, committed by the Red Army in Europe, particularly, in Germany.
Accusations that the hunger in Ukraine in the 1930s was artificially organized.
Other accusations include the Red Terror during Russian civil war, the Great Purge of 1937-1938, Moscow show trials, antisemitic doctors' affair in 1952-1953 and alleged plans to resettle the Jews.
The accusations may go as far as claiming that the whole Russian culture and mentality is inclined towards undemocratic, autocratic, totalitarian government, that Russian culture and/or genetics are polluted by the Mongols during the Tataro-Mongol yoke, that Russian culture is collectivistic, state-centered and opposed to European culture that values personal freedom and human rights, etc.
There is also an anti-Russian ideology, originated in Poland, and called "Prometheism" that alleges that many peoples conquered by Russia are suffering oppression by the Russian state (which is called a prison of peoples), and that those nations should help each other in combatting Russian imperialism.