Ayman al-Zawahiri (1951-, a physician of Egyptian origin, is believed to be the deputy leader and principal operational planner of al-Qaeda. Born into a wealthy medical family, he trained as a pediatrician at al-Azhar University.
He displaced Abd al-Qadir bin ‘Abd al-‘Aziz as leader of Egyptian Islamic Jihad; the two have accused one another of plagiarism. He also claimed that Jamaat al-Islamiyya joined al-Qaeda; while members may have done so, the leadership disavowed a merger.
While he is considered strategically and tactically skilled, his Islamist knowledge has been questioned. In 2001, he produced “Knights under the Prophet’s Banner,” extolling al-Qa’ida’s strategy, which derives from a number of Salafist writers, and (most notably those of Sayyid Qutb) gives his framework of his interpretation of jihad.  He is a believer in the theological doctrine of al-wala’ wa’l-bara’, rejecting any alliance with other than strict Muslims, and takfir, the destruction of infidels and apostates.
- Brian Drinkwine (January 26, 2009), "The Serpent in Our Garden: Al-Qa'ida and the Long War", Carlisle Papers, Strategic Studies Institute, U.S. Army War College, p. 7
- Joas Wagemakers (Fall, 2008), "Framing the "threat to Islam": al-wala' wa al-bara' in Salafi discourse", Arab Studies Quarterly (ASQ)