Bin Laden is thought to be in the Afghan-Pakistan border region
Osama Bin Laden is top of the US most wanted list.
He is accused of being behind a number of atrocities, including the 1998 bombing of two US embassies in East Africa and - most notoriously - the attacks on New York and Washington on 11 September 2001.
Since then, his al-Qaeda network has been linked indirectly to bombings on the island of Bali in Indonesia and its capital Jakarta, as well as with devastating suicide attacks in Casablanca, Riyadh and Istanbul.
After 9/11, al-Qaeda leaders are believed to have regrouped in Pakistan's tribal areas.
Bin Laden is still thought to be hiding in the mountainous region near the border between Pakistan and Afghanistan.
Successive operations involving coalition troops inside Afghanistan, and Pakistani forces along their side of the border, have so far failed to track down the al-Qaeda leader, and his precise whereabouts remain a mystery.
Mild-mannered and polite
Those who have met Bin Laden describe him as a mild-mannered man, who is generally polite and hospitable to strangers, yet he has become the most hated and implacable opponent of the US and all it stands for.
Born in Saudi Arabia in 1957 to a wealthy Yemeni father and a Syrian mother, he had a comfortable childhood.
BIN LADEN OBJECTIVES
Religious war against America and American interests
Remove US forces from Saudi Arabia and the Gulf
Liberate Jerusalem from Israelis
Overthrow the "un-Islamic" governments of the region
Restore the Caliphate, or pan-Islamic ruler
Like his father, who had made his fortune from the construction business and had close ties with the Saudi royal family, the young Bin Laden had religious leanings.
At school and university, he was a member of the Muslim Brotherhood.
When the Soviets invaded Afghanistan in 1979, he went to Pakistan, where he met Afghan rebel leaders resisting the occupation.
Later, he returned to Saudi Arabia to collect money and supplies for the Afghan resistance, the mujahideen.
He made further trips, delivering aid and arms, and eventually joining the fight against the Soviets.
As a wealthy Saudi, he stood out and acquired a following.
Born in Saudi Arabia
Fought against Soviets in Afghanistan
Ploughed inherited fortune into armed activities
Reported to have at least three wives
Suffers from kidney disease
Last video message broadcast October 2004
Egyptians, Lebanese, Turks and others - numbering thousands in Bin Laden's estimate - joined their Afghan Muslim brothers in the struggle against a Soviet ideology that spurned religion.
Bin Laden opened a guesthouse in Peshawar - a stopping-off point for Arab mujahideen fighters. Eventually, their numbers became so large he built camps for them inside Afghanistan.
He gave the umbrella group for his guesthouse and camps a name: al-Qaeda, Arabic for "the base".
As a military commander, Bin Laden was respected for his organisational skills, his bravery and, above all, for his ability to survive.
The Afghan jihad against the Soviet army was backed by American dollars and had the blessing of the governments of Saudi Arabia and Pakistan.
Bin Laden is accused of involvement in the 1998 US embassy bombings
After the Soviet withdrawal, the "Arab Afghans", as Bin Laden's faction came to be called, looked forward to a warm welcome at home.
But Bin Laden quickly became disillusioned by the lack of recognition for his achievements.
This turned to anger when the Saudis turned down his offer to provide an army of mujahideen to defend the kingdom after the Iraqi invasion of Kuwait.
Instead, half a million US soldiers were invited on to Saudi soil - a historic betrayal in Bin Laden's eyes.
Bin Laden became an out-and-out opponent of the Saudi regime and began to direct his efforts against the US and its allies in the Middle East.
In 1991, he was expelled from the country because of his anti-government activities.
Period of radicalisation
He spent the next five years in Sudan, where he used his money to fund a number of infrastructure projects for the Islamist government in Khartoum.
The Saudi government is reported to have sought reconciliation but, when this failed, it froze his bank accounts and stripped him of his Saudi citizenship.
The US put pressure on Sudan's government to expel him, prompting Bin Laden's return to Afghanistan where he became increasingly messianic and radical.
By the mid-1990s, he was calling for a global war against Americans and Jews and in 1998, he issued his famous fatwa (religious ruling), amounting to a declaration of war against the US.
Two simultaneous bomb attacks against US embassies in Kenya and Tanzania followed a few months later.
Bin Laden never acknowledged responsibility, but several of those arrested for their part in the bombings named him as a backer.
Al-Qaeda's motivations and aims are varied, but include avenging perceived wrongs against Muslims, imposing a single Islamic political leadership over the Muslim world, and driving Americans and other non-Muslims from Saudi Arabia, the home of Islam's holiest sites.
After the 2001 attacks Bin Laden made a number of recorded statements.
Later these became much less frequent, though several recent audio messages have been attributed to him - including one in September 2009 that called on US to stop its military campaign against al-Qaeda.
Audio messages have carried still images thought to show Bin Laden. The al-Qaeda leader is believed to have stopped making video messages, possibly as a security precaution or because of poor health.
But many analysts believe that even if Bin Laden were to die or be killed, his organisation has taken on a life of its own, and would continue to inspire Islamic militancy around the world.