Sergey Fyodorovich Oldenburg (Russian: Серге́й Фёдорович Ольденбу́рг; 26 September 1863, in Byankino, Transbaikal Oblast – 28 February 1934, in Leningrad) was a Russian orientalist who specialized in Buddhist studies. He was a disciple of Ivan Minayev, the founder of Russian Indology.
Sergey Feodorovitch Oldenburg was born in Russia on 26 September 1863, in Byankino, Transbaikal Oblast. His father was of the lesser nobility; his grandfather was a full general in the Imperial Russian Army. During the 1880s while at St. Petersburg University Oldenburg participated in the Scientific-Literary Association of Students, a brotherhood which shared liberal and radical ideals. Here he met Aleksandr Ulyanov as they were both in the inner circle of this organisation. Ulyanov dropped out of the inner circle when he started to plan an assassination attempt on the life of emperor Alexander III. The attempt failed, and following the execution of Ulyanov in 1887, his brother, Vladimir Lenin visited Oldenburg in St Petersburg in 1891. Oldenburg had just returned from a two-year trip to London, Paris, and Cambridge.
Oldenburg was elected to the Russian Academy of Sciences in 1900, and he served as its permanent Secretary from 1904 to 1929. From 1905 he became active in the Imperial Russian Geographical Society. In 1909–10 and 1914–15, he travelled in central Asia, where he discovered Sanskrit texts. He instigated scientific expeditions to Tibet and Dzungaria, which brought to light unique Buddhist manuscripts. To publish newly found manuscripts, Oldenburg had launched in 1897 an authoritative edition of Buddhist texts, Bibliotheca Buddhica, which continues to this day.