He is regarded as one of the most powerful militants in the world, a former Islamist preacher who evolved into a global jihadist now threatening to rewrite the map of the Middle East.
Yet Abu Bakr al-Baghdadi, the head of the Islamic State of Iraq and the Levant, remains largely a mystery, even to his followers.
Unlike such iconic figures as al-Qaida leaders Osama bin Laden and Ayman al-Zawahri, only two photos are known to exist of al-Baghdadi, showing a trim-bearded man with thick eyebrows. Al-Baghdadi, whose fighters have seized large swaths of territory in both Syria and Iraq, releases only audio messages. Even when he meets with ISIL commanders, al-Baghdadi is said not to reveal himself.
During such sessions, several men whose faces are covered to conceal their identities are said to enter the room, listening without speaking and then leaving. The commanders are simply told that "one of these was Baghdadi and he heard what you wanted and he will respond at a later time," said Abu Ibrahim al-Raqqawi, an opposition activist in Raqqa, Syria, which ISIL views as its capital.
"No one deals with him except leaders at the highest level," al-Raqqawi said.
The rising prominence of such regional militant groups, including al-Qaida branches, has corresponded in part with internal criticism of al-Zawahri as an inadequate successor to Osama bin Laden.
Al-Baghdadi's fighters have made brutality their calling card, executing detainees in public squares and even crucifying some victims. The current fighting brings him back to familiar turf. His path was shaped by the 2003 U.S.-led invasion of Iraq and included time in a U.S.-run prison.
Born in Samarra, Iraq, in 1971, al-Baghdadi holds a doctorate in Islamic studies from the Islamic University in Baghdad and worked as a teacher and Sunni Muslim preacher before the invasion that toppled the Sunni-dominated government of Saddam Hussein, according to an unofficial biography that has circulated on jihadist websites.
The name al-Baghdadi -- his full name is Ibrahim Awwad Ibrahim Ali Al Badri Al Samarri -- signifies his ties to the Iraqi capital. Al-Baghdadi first fought the Americans and then the emerging Shia-run Iraqi government as a member of the Mujahedeen Army, an Islamist force with nationalistic rather than global ambitions.
Al-Baghdadi is believed to have served time in the U.S.-run prison Camp Bucca during the war -- and it was there, jihadists sources say, that he joined a nascent Iraqi branch of al-Qaida known as al-Qaida in Iraq, founded by Abu Musab al-Zarqawi, who was killed in a 2006 U.S. airstrike.
In 2010, when another ISIL leader was slain, al-Baghdadi was elected its leader.
ISIL was itself affiliated with al-Qaida until al-Baghdadi rebranded the franchise and went international by entering the fray in neighboring Syria in April 2013. Introduction of the Islamic State of Iraq and Syria was made in a 23-minute video of the group's black and white flag flapping over a strictly audio statement.
Al-Zawahri unsuccessfully ordered ISIL to cease operations and return to Iraq. But al-Baghdadi refused and its forces violently seized control of large swaths of northern Syria.