Al-Mu'tassimu Billahi Muhibbuddin Sultan Abdul Halim Mu'adzam Shah ibni Almarhum Sultan Badlishah (28 November 1927 – 11 September 2017) was Sultan of Kedah from 1958 until his death in 2017, and served twice as the King of Malaysia from 1970 to 1975 and from 2011 to 2016. He was the first and only ruler to reign as king twice, as well as the oldest elected to the office.