Vaclovas Biržiška (2 December 1884 – 3 January 1956) was a Lithuanian attorney, bibliographer, and educator.

His father, the physician Antanas Biržiška, declined a professorship at the University of Moscow to practice medicine in the rural areas of Lithuania.

During the conflicts between Lithuania, Poland, and Russia that took place between 1918 and 1920, he served as legal counsel to both Lithuanian and Polish defendants.

After Vilnius was annexed by Poland, he moved to the temporary capital of Lithuania, Kaunas.

After World War II, Biržiška emigrated to West Germany and then to the United States.