Sergius Nikolajewitsch von Bubnoff (15 July 1888 in Saint Petersburg – 16 November 1957 in Berlin) was a geologist and geotechnical engineer with Germano-Baltic ancestry who made important contributions to the rebuilding of geological research in East Germany after World War II.
His brother, Nikolai Nikolaiyevitch von Bubnoff, who was eight years his senior, taught philosophy at the University of Heidelberg.
He died in 1957 at the age of 69 years old as the result of a heart attack and was buried in the cemetery of the evangelical Moravian Church in Niesky.
Serge von Bubnoff studied geology up to and including 1910 at the University of Freiburg at which he was given his doctorate in 1912 with a work about the tectonics of the section of the Dinkelberg located in Basel.
After the end of World War II and the founding of the German Democratic Republic (GDR), Bubnoff became professor and director of the Geological-Paleontological Institute at Humboldt University in Berlin in 1950.
In the year after his death, the Geological Society of the German Democratic Republic, which had named him an honorary chairman in 1954, founded the Serge-von-Bubnoff-Medaille.