Doctor Sivasubramanian Chandrasegarampillai is a fictional character from Arthur C. Clarke's Space Odyssey series. He is mentioned in the novelization of 2001: A Space Odyssey as a scientist who instructed the computer HAL 9000 in its basic functions. He is a main character in 2010: Odyssey Two as a member of the joint Russian-American expedition to Jupiter on board the Soviet spacecraft Alexei Leonov. He is also briefly mentioned by an elderly Heywood Floyd in the novel 2061: Odyssey Three. In the movie version of 2010, Dr. Chandra was played by Bob Balaban and is referred to as Dr. R. Chandra.