Rajendra Singh (राजेन्द्र सिंह ठाकुुर, 29 January 1922 – 14 July 2003 ), popularly called Rajju Bhaiya, was the fourth Sarsanghchalak of the Rashtriya Swayamsevak Sangh (RSS). He was chief of that organisation between 1994 and 2000. Rajendra Singh was the first non-Maharashtrian Sarsanghchalak of the RSS. Rajju Bhayya worked as a professor and head of the Department of Physics at Allahabad University but left the job to devote his life to the RSS in the mid-1960s.