Hakeem Noor-ud-Din (also spelt: Hakim Nur-ud-Din) (Arabic: حکیم نور الدین) (c. 1841 – 13 March 1914) was a close companion of Mirza Ghulam Ahmad, the founder of the Ahmadiyya Movement, and was chosen as his first successor on 27 May 1908, a day after his death, becoming the first caliph (Arabic: خليفة المسيح الأول, khalīfatul masīh al-awwal) and leader of the worldwide Ahmadiyya Muslim Community. He was a renowned physician, writer, theologian, and an expert in Arabic and Hebrew.