Ayman Muhammad Rabaie al-Zawahiri (Arabic: أيمن محمد ربيع الظواهري‎, Ayman Muḥammad Rabayaḥ aẓ-Ẓawāhirī; born June 19, 1951) is a prominent leader of al-Qaeda, and was the second and last "emir" of Egyptian Islamic Jihad, having succeeded Abbud al-Zummar in the latter role when Egyptian authorities sentenced al-Zummar to life imprisonment. Al-Zawahiri is a qualified surgeon, and is an author of works including numerous al-Qaeda statements. He speaks Arabic, English and French. Al-Zawahiri is under worldwide embargo by the UN 1267 Committee as a member or affiliate of al-Qaeda.

In 1998 al-Zawahiri formally merged Egyptian Islamic Jihad into al-Qaeda. According to reports by a former al-Qaeda member, he has worked in the al-Qaeda organization since its inception and was a senior member of the group's shura council. He is often described as a "lieutenant" to Osama bin Laden, though bin Laden's chosen biographer has referred to him as the "real brains" of al-Qaeda.

Ayman al-Zawahiri is usually spelled Zawahiri (the pronunciation of his name in his native Egyptian Arabic), but is sometimes spelled "Dhawahiri" if transliterated directly from Modern Standard Arabic, aka Literary Arabic, in certain academic circles. Using the Intelligence Community Standard for the Transliteration of Arabic Names, it is spelled Zawahiri.