Nasser al-Din Shah Qajar (16 July 1831 – 1 May 1896) is the King of Iran from 17 September 1848 to 1 May 1896 when he is assassinated.

He was the son of Mohammad Shah Qajar and Malek Jahan Khanom, Mahd-e Olia and the third longest reigning monarch king in Iranian history after Shapur II of the Sassanid Dynasty and Tahmasp I of the Safavid Dynasty.

He has sovereign power for close to 50 years and is also the first Persian monarch to ever write and publish his diaries.