Sheikh Hassan Nasrallah, Secretary-General of Hezbollah - or Party of God - has re-positioned the Shia organisation as a major player in Lebanese politics.
Hezbollah's leader Sheik Hassan Nasrallah
Viewed by many Israelis as a terrorist and religious fanatic, Sheikh Nasrallah has become a vastly influential figure in Lebanon.
Diplomats and others who have met him describe him as highly intelligent, widely-read and politically astute.
Hassan Nasrallah was born in 1960 in southern Beirut, one of nine children of a poor grocer. After Lebanon erupted into civil war in 1975, his family fled the city to its ancestral village in the south of the country.
As a teenager, he studied both politics and the Koran, spending three years at the Shia seminary in Najaf in Iraq, where he met Sayyad Abbas Musawi, his predecessor as leader of Hezbollah.
In 1978, Sheikh Nasrallah was expelled from Iraq and became heavily involved in Lebanese politics, first as a member of the Shia Amal militia, then as the Amal political representative for the Bekaa region.
Praised suicide bombers
He also studied and taught religion at a school founded by Musawi in the Baalbek area.
But Israel's 1982 invasion of Lebanon transformed the situation. Nasrallah and many of his colleagues broke away from Amal, which was being pressured to join a National Salvation Front, which had established relations with Israel.
With the formation of a new organisation, Hezbollah, Sheikh Nasrallah concentrated on political work.
Hezbollah's military wing is believed to have been behind a large number of deadly attacks, hijackings, kidnappings of Westerners, including Terry Waite, and the bombing of the US Marine barracks in Beirut which killed 241 people in 1983.
After Musawi was assassinated by the Israelis in 1992, Sheikh Nasrallah, aged just 32, was elected his successor.
Weeks later a suicide bomber killed 29 people and injured 100 more in an attack on the Israeli embassy in the Argentine capital Buenos Aires.
The former Lebanese prime minister Rafik Hariri was murdered in 2005
Another bombing, of a Jewish community centre in the same city in 1994, killed 85 and injured more than 200.
Hezbollah is widely believed to have been involved in these attacks.
Sheikh Nasrallah then used a twin-track approach, supporting Hezbollah charities while masterminding the low-intensity war with the Israeli Defence Force which ended with its withdrawal from Lebanon in 2000.
More recently, he is believed to have been involved in providing information and intelligence for Palestinian groups. He has praised Palestinian suicide bombers for "creating a deterrence and equalising fear."
And, in the months following the assassination of the former Lebanese Prime Minister, Rafik Hariri, in February 2005, Sheikh Nasrallah - who, tellingly, no longer calls for Lebanon to become an Islamic state - has emerged as an influential arbitrator between the country's many political factions.
Sheikh Nasrallah, his wife and their three children, are said to live simply in a poor area of south Beirut. It is said that he has read books written by the former Israeli prime ministers Ariel Sharon and Benjamin Netanyahu.
His eldest son, Hadi, became a fighter with Hezbollah, and was killed in 1997 during a fire-fight with Israeli troops in southern Lebanon.