Abu Musab al-Zarqawi
Abu Musab al-Zarqawi (1966-2006) was a Jordanian citizen, who led al-Qaeda in Iraq until killed by an American airstrike on June 8, 2006. Zarqawi, while highly focused on attacking U.S. forces, also supported Islamic sectarian conflict between Iraqi Sunni and Shi'a Muslims. Al-Qaeda derives from Sunni doctrines, which call for the re-establishment of the Caliphate, which conflict with Shi'a beliefs.
He was considered an effective tactician, but less of an ideologue and theologian.  A close advisor, variously identified as Abu Rahman or Abu Abdul-Rahman al-Iraqi, was killed in the same bombing. It is unclear if that person was his spiritual adviser alone, or his deputy; other accounts say a man named Abu Abdul-Rahman al-Iraqi is the new head of al-Qaeda in Iraq. 
Raised in the industrial area of al-Kasara in al-Zarqa (aka al-Zarqaa), he dropped out of school after his father's death, and became known for brutality, and was jailed for drug possession and sexual assault. Acquaintances, however, said he remained extremely devoted to his mother. He was of Bedouin ancestry; there is disagreement if he identified as Palestinian. 
Refugee camps and Salafism
He began to frequent nearby Palestinian refugee camps, where he became a Salafist. This appeared to give him calm; he held a conventional job and married.
In 1989, he entered the Afghanistan War (1978-92), more involved in journalism than in direct combat, although he probably fought Russian troops at Khost under commander Abu al-Harith al-Salti aka Farouq. He wrote for al-Bonian al-Marsous (The Strong Wall); his brother in law, Abu Saleh al-Hami was a correspondent for al-Jihad.
Increasing organizational role
In Pakistan, he met Abu Muhammad al-Maqdisi, considered an important radical scholar, second only to Abdullah Azzam. The two returned to Jordan and formed an organization, Bayt al-Imam (House of the Leader) for returnees from Afghanistan. This paralleled Makhtab al-Khidimat (Services Office) set up, in Pakistan, by bin Laden and Azzam. This may have been the start of their cooperation.
Back in Jordan, he and al-Maqdisi were arrested in in March 1994 on charges of plotting to overthrow the government. They did not defend themselves, but instead charged the government, being sentenced to 15 years. In Suwaqa prison, al-Maqdisi, assisted by Zarqawi, led a prisoner group as Zarqawi studied.
Zarqawi became increasingly radical, and he and al-Maqdisi no longer spoke. Zarqawi, as the only Afghan combat veteran, confronted the authorities, aided prisoners, and gained loyalty. He was released in a 1999 amnesty.
He returned to Afghanistan by 2000, and, while he and bin-Laden were sympathetic, they had separate organizations. In particular, Zarqawi focused on building support networks based in Europe, while bin-Laden's were in Pakistan.
He was based near Herat; there were reports he was working on chemical weapons. His plan to bomb a hotel in Jordan was broken up by Jordanian security. He was also part of a plot to bomb a hotel in Amman, Jordan, frequented by American and Israeli tourists, during millennial celebrations. Jordanian security forces broke it up.
After 9/11 and 2003, he was been injured in a missile strike on one of his bases.  One report indicates he had a leg amputated, and escaped to Iran. From Iran, he went to Baghdad for medical care. . During his recovery, he met with other extremists and established a base. Before the Iraq War, however, he went to Syria, and Lebanon, allegedly meeting with Hezbollah.  Some of the details here may be inconsistent, since the Shi'a-oriented Hezbollah would not seem a likely ally of a Salafist organization.
In 2003, he entered Iraq, allying with the Kurdish organization, Ansar al Islam, which had linkages with al-Qaeda. He continued, however, to have a separate organization, Tawhid wal Jihad (Unity and Jihad). While he became closer to al-Qaeda, he had a different organizational approach, reported to be more centrally directed and multinational than al-Qaeda's signature decentralized clandestine operations.
- Ellen Knickmeyer and Jonathan Finer (June 8, 2006), "Insurgent Leader Al-Zarqawi Killed in Iraq", Washington Post
- Trevor Stanley, Abu Musab al-Zarqawi: The Usama bin Laden of Iraq, Perspectives on World History and Current Events
- "Zarqawi supporters swear loyalty", Associated Press, June 10, 2006
- Abu Musab al-Zarqawi, Globalsecurity
- Matthew Levitt (February 6, 2003), "The Zarqawi Node in the Terror Matrix: Linking the terrorists", National Review Online
- Michael Radu (June 8, 2006), E-Notes: The Demise of Abu Musab Al-Zarqawi