Roy, 78, breathed his last at the All India Institute of Medical Sciences, the Revolutionary Democratic Front (RDF) said in a statement. In line with his final wish, his body was donated to the AIIMS for medical research.
According to RDF president Varavara Rao, Roy joined the then undivided Communist Party of India in 1963 before switching over to the CPI-M and, later, the Maoist ranks.
After his arrest in 2005, Roy spent seven years in various jails. He was released for medical treatment on bail bond when it appeared that he had less than a year to live.