Abu Musab al-Zarqawi rose from the life of a street thug in Jordan to become the symbol of "holy war" in Iraq, masterminding the bloodiest suicide bombings of the insurgency, beheading hostages and helping push Iraq into a spiral of sectarian violence with vicious attacks against Shiites.
The 39-year-old Zarqawi, slain in a U.S. air strike Wednesday night, was instrumental in turning the swift U.S. invasion of Iraq in 2003 into a grueling counterinsurgency fight, helping draw Arab militants into what he depicted as a war for Islam against the American "crusaders" and Shiite "infidels."
Zarqawi was not the only insurgency leader. Homegrown Sunni Iraqi guerrillas — believed to have tense relations with Zarqawi — are thought to have had an equal or even greater role in deadly attacks on U.S. and Iraqi forces and Shiites.
Still, Zarqawi became the symbol of the jihadi — or "holy war" — movement, nicknamed the "slaughtering sheik" by his supporters across the Arab world. He is believed to have personally beheaded at least two American hostages, Nicholas Berg in April 2004 and Eugene Armstrong in September 2004. Grisly videos of the slayings were posted on the Internet, part of the revolutionary Web-based propaganda campaign that was key to Zarqawi's movement.
Zarqawi vowed fealty to Al Qaeda leader Usama bin Laden in October 2004 and had the same bounty on his head from the U.S. military — $25 million — as bin Laden.
But he played a dramatically different role: While bin Laden was the hidden leader, issuing statements from hiding in Pakistan's border region with Afghanistan, Zarqawi portrayed himself as the warrior on the front lines.
In the past year, Zarqawi moved his campaign beyond Iraq's borders, carrying out a Nov. 9, 2005, triple suicide bombing against hotels in Amman that killed 60 people, as well as other attacks in Jordan and even a rocket attack from Lebanon into northern Israel.
He also sought to spread Sunni-Shiite strife across the Middle East. In an audiotape posted on the Web last week, he lectured his fellow Sunnis to stand up against Shiites and railed against Shiites for four hours, calling them enemies of Islam.
In April, he released a videotape showing his face for the first time in an apparent attempt to reinforce his image as the leader of Iraq's insurgents and a hero to Sunni extremists. The video emphasized dramatic, iconic images of Zarqawi, showing him in a desert landscape firing a machine gun.
The U.S. military tried to undermine that image, issuing what it said were "out takes" of that video captured in a raid, showing Zarqawi fumbling with the machine gun.
Born Ahmad Fadhil Nazzal al-Khalayleh on Oct. 20, 1966, in Jordan, Zarqawi grew up in the industrial town of Zarqa, from which he eventually took his nom de guerre. He was one of 10 siblings in a poor branch of the prominent Bani Hassan Bedouin tribe, which publicly renounced all ties to him after the hotel bombings in Amman.
As a teenager, he was known as a thug, drinking alcohol and getting in street fights. He was jailed for six months for raping a girl, according to Jordanian security officials.
He then embraced Islamic militancy, making his first trips to Afghanistan in the 1980s before returning to Jordan, where he was arrested in the mid-1990s.
It was in a Jordanian prison that he solidified his radical ideology. He shared a cell block with militant cleric Isam Mohammed al-Barqawi, known as Abu Muhammed al-Maqdisi, who became his spiritual mentor in "takfir" — an extremist strain of Islam that brands its enemies "kafirs" or "infidels" worthy of death.
After being released in an amnesty, Zarqawi went in 1999 to Afghanistan, where he formed links with bin Laden. He fled Afghanistan during the U.S.-led war that ousted the Taliban in late 2001, passing through Iran to Iraq, according to U.S. officials and militant biographies of Zarqawi posted on the Web.
His followers' first operations may have been in his homeland: Jordan has sentenced him to death in absentia for masterminding the October 2002 slaying of Laurence Foley, a diplomat and administrator of U.S. aid programs in Jordan.
Soon after, his movement carried out two major suicide blasts in August 2003 — four months after Saddam's fall — that many see as marking the start of the insurgency in Iraq.
The first hit the U.N. headquarters in Baghdad, killing 22 people, including the top U.N. envoy to Iraq, Sergio Vieira de Mello, and prompting the United Nations to pull its personnel out of the country.
The second targeted a Shiite shrine in Najaf that killed more than 85 people, including Shiite leader Ayatollah Mohammed Baqir al-Hakim.
For more than two years, Zarqawi wreaked mayhem across Iraq, his strikes targeted not only to inflict maximum casualties but also to weaken Iraq's fledgling security forces, cause political damage, or enflame sectarian violence.
His group claimed responsibility for the bloodiest single attack of the insurgency: the February 2005 suicide bombing against Iraqi security recruits in Hillah that killed 125 people.
His fighters are believed to be behind a string of suicide bombings against Shiites in the holy city of Karbala and a police station north of Baghdad on Jan. 5, 2006, that killed at least 130 people — only weeks after a landmark parliament election.
A May 18, 2004, a car bomb detonated by Zarqawi's fighters assassinated the president of the now disbanded Iraqi Governing Council, Izzadine Saleem.
The string of kidnappings of Westerners by his followers terrorized foreign workers in Iraq, forcing them to limit movements and take up costly security precautions.
Among the other hostage slayings claimed by Al Qaeda in Iraq were American Jack Hensley, British engineer Kenneth Bigley, Kim Sun-il of South Korea and Shosei Koda of Japan, whose decapitated body was found dumped and wrapped in an American flag.
Al Qaeda in Iraq also kidnapped and killed the top Egyptian diplomat in Iraq and two Algerian diplomats, part of a campaign aimed at scaring Arab nations from sending full ambassadors to Baghdad in support of the new, Shiite-led government.
But in the last months of his life, there were signs Zarqawi's attacks on civilians were eroding his support. The triple hotel bombing in Amman — which killed mostly Sunni Muslims — outraged many in Jordan and even brought criticism from other Islamic militants.
In January, Zarqawi announced that his group was joining an umbrella organization of Iraqi insurgents called the Shura Council of Mujahedeen. The move was seen as an attempt to give an Iraqi face to Zarqawi's movement, which was believed to be mainly made up of non-Iraqi, Arab fighters.
Confirming Zarqawi's death, his deputy, known as Abu Abdel-Rahman al-Iraqi, vowed to continue the fight.
"The death of our leaders is life for us," he said in a Web statement. "It will only increase our persistence in continuing holy war so that the word of God will be supreme."