Count Eustachy Tyszkiewicz, Leliwa coat of arms, (18 April 1814 – 27 August 1873) was a Polish nobleman, Russian government official, archaeologist and historian of the former Grand Duchy of Lithuania and White Ruthenia, incorporated into the Russian Empire after the Partitions of Poland.
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 (Vilna, Wilno), 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.