Rajiv Ranjan Singh alias Lalan Singh (born 24 January 1955) is an Indian politician and Member of Parliament representing Munger in the 17th Lok Sabha from Janata Dal (United). He is National party president of JDU (Janta Dal United). He was also the former JD(U) Bihar unit President. He was nominated as a member of the Bihar Legislative Council in June 2014 after his defeat in the May 2014 Lok Sabha elections. He was a member of the 15th Lok Sabha of India and represented Munger Lok Sabha constituency of Bihar. He also represented Begusarai constituency in the 14th Lok Sabha of India.