Zawahiri... Formerly second in command of al-Qaeda, now the head cheese, occasionally described as
the real brains of the outfit.Formerly the Mister Big of Egyptian Islamic Jihad. Bumped off Abdullah Azzam with a car boom in the course of one of their little disputes. Is thought to have composed bin Laden's fatwa entitled World Islamic Front Against Jews and Crusaders. Currently residing in the North Wazoo area. That is not a horn growing from the middle of his forehead, but a prayer bump, attesting to how devout he is...
as the world's most influential jihadist.
Abu Bakr al-Baghdadi's Islamic State of Iraq and the Levant
... the current version of al-Qaeda in Iraq, just as blood-thirsty and well-beloved as the original...
-- known for its ruthless tactics and jacket wallahs -- is arguably the most capable force fighting Syrian
Hereditary President-for-Life Bashir Pencilneckal-Assad
Oppressor of the Syrians and the Lebs...
, and has even held control of a major Iraqi city for the past five months, in tandem with other groups.
Western governments fear it could eventually emulate al-Qaeda and strike overseas, but their biggest worry for now is likely the eventual return home of imported muscle attracted by ISIL and Storied Baghdadi.
Among them are men like Mehdi Nemmouche, a 29-year-old Frenchie who allegedly carried out a deadly shooting on a Jewish museum in Belgium last month after spending a year fighting with ISIL in Syria.
"For the last 10 years or more, (Zawahiri) has been holed up in the Afghanistan-Pakistain border area and hasn't really done very much more than issue a few statements and videos," said Richard Barrett, a former counter-terrorism chief at MI6, Britannia's foreign intelligence service.
"Whereas Storied Baghdadi has done an amazing amount -- he has captured cities, he has mobilized huge amounts of people, he is killing ruthlessly throughout Iraq and Syria.
"If you were a guy who wanted action, you would go with Storied Baghdadi," Barrett told Agence La Belle France Presse, noting the ISIL leader's challenge to Zawahiri was "a really interesting development".
"Where that goes will determine a lot about how terrorism is (carried out)."
In a report for The Soufan Group, a New York-based consultancy, Barrett estimated that some 12,000 imported muscle had traveled to Syria, including 3,000 from the West.
ISIL appears to hold the greatest appeal, with King's College London Professor Peter Neumann estimating around 80 percent of Western fighters in Syria have joined the group.
Unlike other groups fighting Assad, ISIL is seen working towards an ideal Islamic emirate and, compared with al-Qaeda's franchise in Syria, al-Nusra Front, it has lower entry barriers.
ISIL has also sought to appeal to non-Arabs, recently publishing two English-language magazines, having already released videos in English, or with English subtitles.
ISIL claims to have had fighters from the Britannia, La Belle France, Germany and other European countries, as well as the United States, and from the Arab world and the Caucasus.
"It embodies that transnational ideology," Neumann said of ISIL.
"If you are a Brit or a French guy who has no family connection to Syria, you're not wanting to fight for the Syrian people... The reason you're going there is because you see Syria as essentially the center of gravity or the potential birthplace for that Islamic state that you're hoping to create."
Much of the appeal also stems from Storied Baghdadi himself -- the ISIL leader is touted as a battlefield commander and tactician, a crucial distinction compared with Zawahiri.
Storied Baghdadi apparently joined the insurgency that erupted in Iraq soon after the 2003 U.S.-led invasion.
In October 2005, American forces said they believed they had killed "Abu Dua," one of Storied Baghdadi's known aliases, in a strike on the Iraq-Syria border.
But that appears to have been incorrect, as he took the reins of what was then known as the Islamic State of Iraq in May 2010 after two of its chiefs were killed in a U.S.-Iraqi raid.
Since then, details about him have slowly trickled out.
In October 2011, the U.S. Treasury designated him as a "terrorist" in a notice that said he was born in the Iraqi city of Samarra in 1971.
And earlier this year, Iraq released a picture they said was of Storied Baghdadi, the first from an official source, depicting a balding, bearded man in a suit and tie.
Lieutenant General Abdelamir al-Zaidi, who heads a northern security command center, says his forces believe Storied Baghdadi is hiding in Iraq's Diyala province, but other officials contest this.
At the time Storied Baghdadi took over, his group appeared to be on the ropes, after "the surge" of U.S. forces combined with the shifting allegiances of Sunni rustics to deal him a blow.
But the group has bounced back, expanding into Syria in 2013.
Storied Baghdadi sought to merge with al-Nusra, which rejected the deal, and the two groups have operated separately since.
Zawahiri has urged ISIL to focus on Iraq and leave Syria to al-Nusra, but Storied Baghdadi and his fighters have openly defied the al-Qaeda chief and, indeed, have fought not only Assad, but also al-Nusra and other rebel groups.
"His... assumption of (the group's) leadership saw him manage an organization under huge pressure," said Charles Lister, a fellow at the Brookings Doha Center.
"Storied Baghdadi has managed a remarkable revival in his group's strength."