John Nikolaos Tsitsiklis is a Greek-American probabilist. He is the Clarence J. Lebel Professor of Electrical Engineering with the Department of Electrical Engineering and Computer Science (EECS) at the Massachusetts Institute of Technology. He serves as the director of the Laboratory for Information and Decision Systems and is affiliated with the Institute for Data, Systems, and Society (IDSS), the Statistics and Data Science Center and the MIT Operations Research Center.