Naser al-Din Shah Qajar(17 July 1831 – 1 May 1896) was the fourth Shah of Qajar Iran from 5 September 1848 to 1 May 1896 when he was assassinated. He was the son of Mohammad Shah Qajar and Malek Jahan Khanom and the third longest reigning monarch in Iranian history after Shapur II of the Sassanid dynasty and Tahmasp I of the Safavid dynasty. Nasser al-Din Shah had sovereign power for close to 51 years.

He was the first modern Persian monarch who formally visited Europe and wrote of his travels in his memoirs. A modernist, he allowed the establishment of newspapers in the country and made use of modern forms of technology such as telegraph, photography and also planned concessions for railways and irrigation works. Despite his modernizing reforms on education, his tax reforms were abused by people in power, and the government was viewed as corrupt and unable to protect commoners from abuse by the upper class which led to increasing anti-governmental sentiments. He was assassinated when visiting a shrine in Rayy near Tehran.