Shilendra Kumar Singh or S.K. Singh (24 January 1932 – 1 December 2009) was an Indian diplomat. He was Governor of Arunachal Pradesh from December 2004 to September 2007 and Governor of Rajasthan from September 2007 until he died in office in December 2009.Singh was Indian Foreign Secretary from 1989 to 1990. Prior to becoming Governor of Arunachal Pradesh, he was secretary-general of a think tank in Delhi, the University of Pennsylvania Institute for the Advanced Study of India.