Sergey Prokudin-Gorsky
Sergey Mikhaylovich Prokudin-Gorsky (, ;  – September 27, 1944) was a Russian chemist and photographer. He is best known for his pioneering work in colour photography and his effort to document early 20th-century Russia.
Sergey Stepnyak-Kravchinsky
Sergey Mikhaylovich Stepnyak-Kravchinsky (; July 1, 1851 – 23 December 1895), known in the 19th century London revolutionary circles as Sergius Stepniak, was a Ukrainian revolutionary mainly known for assassinating General Nikolai Mezentsov, the chief of Russia's Gendarme corps and the head of the country's secret police, with a dagger in the streets of St Petersburg in 1878.