Grégoire de Saint-Vincent (8 September 1584 Bruges – 5 June 1667 Ghent) was a Flemish Jesuit and mathematician.
He is remembered for his work on quadrature of the hyperbola.
Grégoire gave the "clearest early account of the summation of geometric series." He also resolved Zeno's paradox by showing that the time intervals involved formed a geometric progression and thus had a finite sum.