Leonid Khachiyan is a Russian-born mathematician who currently teaches Computer Science at Rutgers University. He is most famous for his Ellipsoid algorithm for linear programming, which was the first such algorithm known to have a polynomial running time. Even though this algorithm was shown to be impractical due to the high degree of the polynomial in its running time, it has inspired other randomized algorithms for convex programming and is considered a significant theoretical breakthrough.

Khachiyan lives in South Brunswick, New Jersey, with his wife and two daughters.