Raj Kumar Singh (RK Singh ), is a former Union home secretary and a former Bihar-cadre IAS officer of 1975-batch. Singh has been a member of the Parliament since 2014 representing Arrah constituency in Bihar. He is popularly known for arresting BJP veteran leader L K Advani during his Rath Yatra, when he was the district magistrate of Samastipur in October, 1990. During his tenure as the Union Home Secretary under UPA, Singh had released names of RSS members who were allegedly part of the Hindu extremist group responsible for blasts on Samjhauta Express and in Malegaon, Maharashtra.

In February 2016, Singh has also criticised former Home Minister P Chidambaram over his remarks that the case of Parliament attack convict Afzal Guru, who was hanged in 2013, “was perhaps not correctly decided”. He had also accused Chidambaram of political interference in changing the affidavit in Ishrat Jahan encounter case. Singh has made bridges with the BJP leadership in less than two years, taking on the leadership on ticket distribution following the debacle in 2015 Bihar elections.

Singh joined the BJP in 2013 and contested the 2014 Lok Sabha election from Arrah and had defeated RJD candidate Bhagwan Singh Kushwaha. In 2019 Lok Sabha election again, he retained the seat by defeating the Communist Party of India (Marxist-Leninist) candidate Raju Yadav.Singh was part of the Prime Minister Narendra Modi’s cabinet at the Centre through both election wins. Currently, he holds the portfolio of Minister of New and Renewable Energy.