Nūr ad-Dīn Maḥmūd Zengī (نور الدين محمود زنگي; February 1118 – 15 May 1174), commonly known as Nur ad-Din (lit. "Light of the Faith" in Arabic), was a member of the Turkomen Zengid dynasty, which ruled the Syrian province (Shām) of the Seljuk Empire. He reigned from 1146 to 1174. He is regarded as an important figure of the Second Crusade.