Abdulaziz ibn Abdul Rahman ibn Faisal ibn Turki ibn Abdullah ibn Muhammad Al Saud (January 15, 1875 – November 8, 1953), usually known within the Arab world as Abdulaziz and in the West as Ibn Saud, is the first monarch and founder of Saudi Arabia, the "third Saudi state".

He reconquers his family's ancestral home city of Riyadh in 1902, starting three decades of conquests that make him the ruler of nearly all of central and north Arabia.

He consolidates his control over the Najd in 1922, then conquers the Hejaz in 1925.

He extends his dominions into what later becomes the Kingdom of Saudi Arabia in 1932.

As King, he presides over the discovery of petroleum in Saudi Arabia in 1938 and the beginning of large-scale oil production after the Second World War.

He fathers many children, including forty-five sons, and all of the subsequent kings of Saudi Arabia.