Katorga (Russian: ка́торга; IPA: [ˈkatərgə]; from medieval Greek: katergon,κάτεργον galley) was a system of penal servitude of the prison farm type in Tsarist Russia. Prisoners were sent to remote camps in vast uninhabited areas of Siberia—where voluntary labourers were never available in satisfactory numbers—and forced to perform hard labour.

"Katorga" was within the normal judicial system of (Imperial) Russia. It had many of the features associated with concentration camps: confinement, simplified facilities (as opposed to prisons), and forced labor, usually on hard, unskilled or semi-skilled work.

Katorgas were established in the 17th century in underpopulated areas of Siberia and the Russian Far East that had few towns or food sources. Nonetheless, a few prisoners successfully escaped back to populated areas. From these times, Siberia gained its fearful connotation of punishment, which was further enhanced by the Soviet Gulag system that developed from the Katorga camps.

After the change in Russian penal law in 1847, exile and katorga became common penalties to the participants of national uprisings within the Russian Empire. This led to increasing numbers of Poles being sent to Siberia for katorga, where they were known as Sybiraks. Some of them remained there, forming a Polish minority in Siberia.