Count Eustachy Tyszkiewicz h. Leliwa (Lithuanian: Eustachijus Tiškevičius, Belarusian: Евста́фий Пи́евич Тышке́вич, Russian: Евста́фий Пи́евич Тышке́вич; 1814, Logoisk – 1874 in Vilna) was a Polish noble, archaeologist and historian from the former Grand Duchy of Lithuania and White Ruthenia, then part of the Russian Empire. He was noted as the first archaeologist with academic and systematical approach to studies of in the Belarusian, Lithuanian, Latvian and Estonian lands, and had a great influence on the upcoming generations of archaeologists.
Eustachy was a brother of historian Konstanty Tyszkiewicz.
In 1855 he founded the Archaeological Commission in Vilna (now Vilnius). In 1858 he also founded the Museum of Antiquities (Muzeum Starożytności) there. In 1865, after Governor Mikhail Nikolayevich Muravyov transferred most valuable parts of collection to Moscow and closed the commission, Eustachy went to Biržai and spent most of his time there. He published a study on history of Biržai in 1869. Tyszkiewicz died in Wilno, and is buried in Rasos cemetery.
Remaining parts of the museum became the basis of the National Museum of Lithuania.