OmarAliSaifuddin Saadul Khairi Waddien (September 23, 1914 – September 7, 1986) was the Sultan of Brunei from June 4, 1950 until October 4, 1967, and was the chief minister of Brunei from July 1947 until 1959.
He was the fifth son of Sultan Muhammad Jamalul Alam II and became Sultan following the death of his brother Ahmad Tajuddin.
Sultan Omar refused to make Brunei be a part of the new federation of Malaysia.
On 6 September 1941, Al-Marhum Sultan OmarAli Saifuddien married Yang Amat Mulia Pengiran Anak Damit binti Pengiran Bendahara Pengiran Anak Abdul Rahman, the grand-daughter of Al-Marhum Sultan Hashim Jalilul Alam Aqamaddin.
The Sultan OmarAli Saifuddien Mosque, an exquisite example of Muslim architecture, was built in the capital in 1958.
Al-Marhum Sultan Haji OmarAli Saifuddien III passed away peacefully on 7 September1986 and was laid to rest in the Royal Mausoleum bringing to an end an era of transition in Brunei.