Gregory Vlastos (Greek: Γρηγόριος Βλαστός) was a Greek scholar of the 20th century.
Vlastos was born in Istanbul to a Greek father and a Scottish mother, on July 27, 1907. He studied philosophy at Robert College in Istanbul before earning his Ph.D. from Harvard in 1931.
He was a scholar of ancient philosophy, an author of works on Plato and Socrates and a teacher at some distinguished American universities including Cornell and Princeton (1955 - 1976).
He died on October 12, 1991 of cancer in the United States.
His publications include:
- "The Philosophy of Socrates" (1970)
- Platonic Studies (1973)
- Plato's Universe (1975).