Ahmad bin Yahya Hamidaddin was the penultimate king of the Mutawakkilite Kingdom of Yemen, who reigned from 1948 to 1962. His full name and title was H.M. al-Nasir-li-Dinullah Ahmad bin al-Mutawakkil 'Alallah Yahya, Imam and Commander of the Faithful, and King of the Mutawakkilite Kingdom of the Yemen.

The Kingdom of Yemen, officially the Mutawakkilite Kingdom of Yemen, also known simply as Yemen or, retrospectively, as North Yemen, was a state that existed between 1918 and 1962 in the northwestern part of what is now Yemen. Located in the Middle East, the Kingdom of Yemen had an area of 195,000 km2. The country was bordered by Saudi Arabia in the north, and the Aden Protectorate to the south. Its capital was Sana'a from 1918 to 1948, then Taiz from 1948 to 1962. Yemen was admitted to the United Nations on 30 September 1947. From 1962 to 1970, it maintained control over portions of Yemen until its final defeat in the North Yemen Civil War.