Martin Dimitrov Kassabov (Bulgarian: Мартин Димитров Касабов, born 1977) is a Bulgarian mathematician who works as a professor of mathematics at Cornell University, specializing in combinatorial group theory. Kassabov earned a master's degree from Sofia University in 1998. He completed his Ph.D. from Yale University in 2003 under the supervision of Efim Zelmanov. After postdoctoral research at the University of Alberta he joined Cornell as an H. C. Wang Assistant Professor in 2004.