Hassan al-Banna (1906-49)
As a young preacher, Banna pioneered a tradition of social Islam, giving sermons in streets and cafés. He founded the Muslim Brotherhood in 1928, combining political activism with charitable work. Appalled by signs of foreign military and economic dominance, he built the group into a mass movement with a complex governance structure. He was assassinated in a tit-for-tat action by government agents.
Sayyid Qutb (1906-66)
Qutb, a religious theorist, joined the Brotherhood in the 1950s and became a leading political figure. Initially a secularist, he became a hardliner after a decade of imprisonment under Gamal Abdel Nasser. His idea that a revolutionary vanguard must defend "true" Islam shaped modern extremism. Qutb argued that every society - including those of Muslim countries - was worthy of jihad. He was hanged in 1966.
Mohammed Akif (b 1928)
The Brotherhood's supreme leader from 2004-2010, Akif has been involved since 1940. Part of Qutb's paramilitary network, he spent two decades in prison after being detained in 1954; fellow inmates included Mohamed Badie (see below). Since their release in the 1970s, this anti-reformist wing has had a stranglehold over the movement.
Ayman al-Zawahiri (b 1951)
A trained surgeon and the present leader of al-Qaeda, al-Zawahiri joined the Brotherhood at 14, saying that his mission was "to put Qutb's vision into action". The cell he set up evolved into the Egyptian Islamic Jihad, more extremist than the Brotherhood, which officially renounced violence in the late 1960s. Al-Zawahiri met Osama Bin Laden in Saudi Arabia in 1986; his group merged with al-Qaeda in 2001.
Mohamed Badie (b 1949)
A veterinarian and ultra-conservative, Badie became the Brotherhood's eighth supreme leader last year. He is highly respected in his field, but many view him as little more than a puppet for those who wish to maintain the status quo.
Mohammad Mursi (b 1951)
A trained engineer and formerly the Brotherhood's spokesman, Mursi was appointed president of the Freedom and Justice Party, formed in February this year after Hosni Mubarak fell. "It is not an Islamist party in the old understanding - it is not theocratic," he told reporters in Cairo, seeking to reassure them that his party does not wish to impose sharia on Egypt.