The grand imam of Al-Azhar has been appointed by presidential decree since 1961 and the institution receives most of its funding from the state, opening up the post to criticism of being too close to the government.
Tayeb is known for his tough stance against the Muslim Brotherhood, Egypt's largest and most organised opposition group, which remains officially banned despite popular support.
In 2006, he condemned a military-style parade by Brotherhood students at Al-Azhar University in which they wore black facemasks "like Hamas, Hezbollah and the Republican Guard in Iran," he said at the time.
Born in 1946, Tayeb joined an Al-Azhar affiliated school at the age of 10.
He has spent more than 40 years at the institution, receiving a PhD in religion and philosophy from al-Azhar university in 1977 before becoming a faculty member and then dean of the philosophy department.
Tayeb has been in charge of the al-Azhar university since 2003 and was Grand Mufti, Egypt's highest religious legal authority, from 2002 to 2003.
He is widely considered to be a moderate.