The 15th Yang di-Pertuan Agong (Head of State/King) of Malaysia, Muhammad V, Sultan of Kelantan, abdicated today, 6 January 2019. He took office on 13 December 2016 and had therefore close to 3 years left of his term. As I understand it, the Sultan of Perak, Sultan Nazrin Shah, as the Deputy Yang di-Pertuan Agong, will perform the duties of the Yang di-Pertuan Agong until the Conference of Rulers has elected the new king.
My Longest reigns (current monarchs) page has therefore been updated. Obviously the page will soon be updated again after the election has taken place and the new King has taken the oath. The Emperor of Japan, Akihito, has already announced that he will abdicate his throne on 30 April 2019. Hopefully there will be no other changes in the meantime.