Official title ("One who has been made Lord") of the King of Malaysia. Of the thirteen states of Malaysia, nine are traditional monarchies and four are former British colonies. The nine monarchs (called sultans or in a few cases rajas) elect one of their own number for a five-year term as Yang di-Pertuan Agong.
Always a constitutional monarch, the Yang di-Pertuan Agong's powers to refuse assent to federal legislation have been further eroded in recent years.
The elected king is a Malay tradition: one of the nine states, Negeri Sembilan, was itself formed out of nine states (which is what its name means), and the elected ruler of Negeri Sembilan is called the Yang di-Pertuan Besar.
The eleventh Yang di-Pertuan Agong since independence in 1957 was Sultan Salahuddin Abdul Aziz Shah of Selangor, elected head of state in September 1999. He died on 21 November 2001. The regent in the last month has been the Sultan of Terengganu, Mizan Zainal Abidin, who now becomes acting king.
Update. On 12 December the Raja of Perlis, Syed Sirajuddin ibni al-Marhum Syed Putra Jamalullail, was elected the next Yang di-Pertuan Agong.