Mohd Sidek bin Hassan (born 24 June 1951) is the Chairman of Petroliam Nasional Berhad (PETRONAS), the national oil and gas corporation of Malaysia, a position he assumed in July 2012. Prior to joining PETRONAS, Tan Sri served in the Administrative and Diplomatic Service of the Malaysian Civil Service for over 38 years, the last six as the Chief Secretary to the Government of Malaysia.