Imad Mugniyah (1962-2008), killed by a car bomb in Damascus, Syria on December 13, 2008, was linked to several militant Islamist terrorist groups. The Council on Foreign Relations linked him to Hezbollah, and described him as the most wanted terrorist in the world until Osama bin Laden entered the field.  One CFR analyst, Mohamad Bazzi, a former correspondent for Newsday, believes that Israel assassinated him, to send a message to both Hezbollah and Hamas.
Robert Baer believes he was strongly connected to the Iranian Revolutionary Guard Corps, and may have conducted the 1983 bombing of the U.S. embassy in Beirut, as well as being involved with hostage-taking in Beirut. Specifically, according to Baer, he worked for Yasser Arafat before 1982, but became independent of him, although stayed linked to the mysterious IJO. Baer linked him to the TWA Flight 847 hijacking and killing.  The Jamestown Foundation also believed in an Iranian connection as well as Hezbollah activity, and said he spent the 1990s establishing Hezbollah support cells throughout the world. 
The U.S. had indicted him for participation in the TWA Flight 847 hijacking and offered a $5 million reward.
According to the Jamestown Foundation, he was born in Tayr Dibbuth near Tyre in southern Lebanon, in the extended family of extended family of Sheikh Muhammed Jawad Mugniyah, a prominent Lebanese cleric of the Musawi clan. He was 13 when the 1975 Lebanese Civil War started and he joined al-Fatah, staying a member until 1982. During Imad's childhood, his family moved to the Bir al-Abed section of Beirut and he was barely a teenager of 13 years when Lebanon's civil war broke out in 1975 (The Jerusalem Report, August 22, 1991). Recruited into Fatah's Force 17, Yasser Arafat's personal guard force, he probably first learned about explosives from his later brother-in-law, Mustafa Badr al-Din.
"'Mugniyah appears to operate as a bridge between Iran and Hezbollah, working for both and calibrating their agendas...Imad Mugniyah embodies the complexity of where to tackle this terrorism." He is believed to report to Hassan Nasrallah, head of Hizbollah, but also works with the Iranian Ministry of Intelligence and National Security (MOIS) and the al-Qods special operations unit of the Iranian Revolutionary Guard Corps, according to Magnus Ranstorp. He is thought to have Iranian security escorts and an Iranian diplomatic passport. "
In January 2006, Mugniyah reportedly accompanied Iranian President Ahmadinejad to a meeting with Syrian President Bashar al-Assad. He allegedly works within the highest levels of the Iranian Revolutionary Guard Corps and Iranian intelligence and is said to take orders directly from Ayatollah Khamenei.
The Jamestown Foundation quotes Asharq al-Awsat to say that as part of Iranian operations, he was introduced to Osama bin Laden in 1993.  Ali Mohamed testified that he arranged several meetings between bin Laden and Mugniyah in Sudan; Bin Laden admired his use of truck boms in Lebanon, and offered an agreement in which "Hezbollah would provide training, military expertise, and explosives in exchange for money and man power."
This agreement may not have been carried out, as relations between Hezbollah and al-Qaeda have had problems. One factor is that the former is Shi'a and the latter Sunni, and the other is that they are competing for world status, according to Paul Pillar. Nevertheless, there is evidence of organizational cooperation, although not necessarily involving Mugniyah. 
- Elisabeth Smick (updated February 13, 2008; research from 2006), Profile: Imad Mugniyah, Council on Foreign Relations
- Mohamad Bazzi (14 February 2008), Bazzi: Who Killed Imad Mugniyah?, Council on Foreign Relations
- Robert Baer (2002), See no evil: the true story of a ground soldier in the CIA's war on terrorism, Thorndike Press, pp. 92-99
- Carl Anthony Wege (8 September 2008), Terrorism Monitor, Jamestown Foundation
- Eben Kaplan (14 August 2006), The Al-Qaeda-Hezbollah Relationship