Count Eustachy Tyszkiewicz, Leliwa coat of arms, was a Polish noble from the Tyszkiewicz family. He was an archaeologist and historian of the former Grand Duchy of Lithuania and White Ruthenia, then part of the Russian Empire. He is considered the first archaeologist to have undertaken a systematic study of historical sites in Belarus and Lithuania, and was highly influential on succeeding generations of archaeologists. In 1855 he founded the Museum of Antiquities in Vilnius, which is regarded as the predecessor institution of the National Museum of Lithuania. He donated his personal collection of archaeological and historical artifacts to start the museum. He was a younger brother of historian Konstanty Tyszkiewicz.

The House of Tyszkiewicz was a wealthy and influential Polish-Lithuanian magnate family of Ruthenian origin, with roots traced to the times of the Grand Duchy of Lithuania. They held the Polish coat of arms Leliwa. Their nobility was reaffirmed in Polish–Lithuanian Commonwealth and the Russian Empire.