Shortly after the 11 September 2001 attacks, the US issued a list of al-Qaeda suspects. Some have now been captured or killed, and some new names have been added to those still at large.
Few details about key figures have been officially released. BBC News Online pieces together what little is known about some of the key al-Qaeda suspects.
Osama Bin Laden
Osama Bin Laden is the man the US accuses of masterminding the 11 September suicide hijackings and other attacks on US interests.
He has been indicted for the 1998 US embassy bombings in East Africa and the attacks on the USS Cole in October 2000.
He founded al-Qaeda in 1979, originally as a guesthouse in Peshawar for Arab fighters.
Despite an extensive military operation in Afghanistan, it is still not known where he is or even if he is definitely still alive.
Arab broadcasters regularly air recordings of speeches attributed to the fugitive al-Qaeda figurehead.
A video released during the US presidential election in October 2004 showed him warning Americans of new attacks.
Egyptian in origin, Ayman al-Zawahiri is believed to serve as Bin Laden’s spiritual adviser and doctor. He is also the architect of the al-Qaeda ideology.
In 1998, he was the second of five signatories to Bin Laden’s notorious “fatwa” calling for attacks against US civilians.
He was a key figure in the Egyptian Islamic Jihad group, which later merged with al-Qaeda.
Zawahiri has appeared alongside Bin Laden in al-Qaeda videotapes released since 11 September. His wife and children were reported killed in a US air strike in late November or early December 2001.
He has eluded capture despite a $25m bounty on his head. He escaped a reported US air strike targeting him in Pakistan in January 2006, in which a close relative was said to have died.
Zawahiri has been indicted in the US for his role in the US embassy bombings in Africa, and was sentenced to death in Egypt in absentia for his activities with the Islamic Jihad group in the 1990s.
Abu Hamza al-Muhajir
Little is known about the man named as successor to Abu Musab al-Zarqawi, the militant leader of al-Qaeda in Iraq killed in a US air strike.
In a website statement, the al-Qaeda in Iraq group said Abu Hamza al-Muhajir was “knowledgeable” and had a history of fighting a holy war.
Muhajir was not among the names al-Qaeda analysts had expected as a probable successor, and is thought to be a pseudonym.
The US military has said it believes him to be an Egyptian militant based in Baghdad, Abu Ayyub al-Masri.
He is understood to have trained in Afghanistan and helped Zarqawi form the first al-Qaeda cell in Baghdad.
A Saudi, Said is Bin Laden’s brother-in-law and al-Qaeda’s financial controller. He first linked up with Bin Laden in Sudan during the late 1990s.
US investigators believe he wired money to Mohammed Atta, alleged ringleader of the hijackers, shortly before the 11 September attacks on New York and Washington.
An Egyptian in his late 30s, al-Adel is Bin Laden’s security chief.
He is believed to have assumed many of the late Mohammed Atef’s duties in al-Qaeda.
He was a colonel in the Egyptian army but joined the mujahideen fighting to expel the Soviets from Afghanistan.
He is also suspected of teaching militants to use explosives and training some of the 11 September hijackers.
He has been linked to the bombings of US embassies in Kenya and Tanzania in 1998. The US further accuses him of training the Somali fighters who killed 18 US servicemen in Mogadishu in 1993.
In 1987, Egypt accused Adel – whose real name is Muhammad Ibrahim Makkawi – of trying to establish a military wing of the militant Islamic group al-Jihad, and of trying to overthrow the government.
Abu Mohammed al-Masri
Also Egyptian, he is frequently believed to use the name Abdullah Ahmed Abdullah and to be about 40 years old.
He ran al-Qaeda training camps in Afghanistan, including the al-Farooq camp near Kandahar.
He is also believed to have been involved in the East Africa embassy bombings. The US has put a bounty of $5m on his head.
Sulaiman Abu Ghaith
Nominal al-Qaeda spokesman, Abu Ghaith is a Kuwaiti and believed to be in his mid-30s. A former religious studies teacher, he left Kuwait in 2000.
He was stripped of his citizenship after an appearance on Qatar-based al-Jazeera television in which he vowed retaliation for US air strikes against Afghanistan.
Bin Laden can be seen poking fun at him in one of the videotapes released since 11 September.
In July 2003, a Kuwaiti minister said the Iranian government had offered to extradite Abu Ghaith to Kuwait, but that Kuwait had refused to take him. It is unclear whether he is currently in Iranian custody, or indeed in Iran at all.
Thirwat Salah Shirhata
Also Egyptian, Shirhata is al-Zawahiri’s deputy in the Egyptian Islamic Jihad group.
He has received two death sentences in absentia in Egypt for alleged terrorist activities.
Omar al-Faruq, born in Kuwait to Iraqi parents, was one of four “dangerous enemy combatants” to escape from the main US base in Afghanistan in July 2005. All four remain on the run.
Al-Faruq had been arrested in June 2002 in a village an hour from Jakarta in Indonesia. He had married a local woman and seemed to have blended successfully into the community.
Investigators fear that men like al-Faruq have been linking al-Qaeda to other militant Islamic groups in South-East Asia.
Abu Faraj al-Libbi
Abu Faraj al-Libbi was arrested in Pakistan along with five other al-Qaeda suspects in May 2005, after a gun battle in Waziristan, North-West Frontier Province.
He is said to have taken over as third in command of al-Qaeda when his mentor, Khalid Sheikh Mohammed, was captured in 2003.
He is a Libyan who is described as the mastermind of two failed attempts to assassinate Pakistani President Pervez Musharraf.
He is thought to have used Pakistan as his base, and from there was reportedly in contact with militants in the UK. Following his arrest, he was handed over by Pakistan to US custody.
Khalid Sheikh Mohammed
Sheikh Mohammed has been sent to Guantanamo Bay in Cuba. He had been in US custody at an undisclosed location from March 2003, when he was captured in a safe house in Pakistan.
A Kuwaiti from the Baluchistan region of Pakistan, Sheikh Mohammed grew up in a religious family and claims to have joined the Muslim Brotherhood at the age of 16.
After attending college in the United States, he went to Afghanistan to participate in the anti-Soviet jihad. It was there that he is believed to have first met Osama Bin Laden.
According to Sheikh Mohammed, he himself first pitched the idea of the aerial-style attacks on the US, calling for the hijacking of 10 jetliners on both coasts of the US and crashing nine of them.
He features prominently in the US 9/11 Commission Report on how the attacks were carried out, and its authors drew heavily on his statements during interrogations.
Testimony from Sheikh Mohammed was also used by defence lawyers for Zacarias Moussaoui, who was jailed for life in 2006 for his role in the 11 September attacks.
Abu Zubaydah, who is thought to have served as Bin Laden’s field commander, was captured in Pakistan in March 2002 and has now been sent to Guantanamo Bay, Cuba.
The Americans describe him as a “key terrorist recruiter and operational planner and member of Osama Bin Laden’s inner circle”.
Zubaydah, who is believed to have been born to Palestinian parents in Saudi Arabia, is also known as Zayn al-Abidin Mohammed Husain and Abd al-Hadi al-Wahab but has used dozens of other aliases.
He has strong connections with Jordanian and Palestinian groups and was sentenced to death in his absence by a Jordanian court for his role in a thwarted plot to bomb hotels there during millennium celebrations.
US officials believe he is also connected to a plan to blow up the US embassy in Sarajevo, and a plot to attack the US embassy in Paris.
According to a Senate report, Zubaydah has told US interrogators that while he believed some al-Qaeda members had good personal relationships with Iraqi government officials he was unaware of any real relationship between Baghdad and the network.
Captured in Pakistan in September 2002, the Yemeni national is said to have become a key member of the al-Qaeda cell in Hamburg, Germany, after seeking asylum there in the late 1990s.
According to officials, he met Mohammed Atta, the leader of the Hamburg cell and one of the alleged masterminds of the 11 September attacks, through a local mosque in 1997.
Intelligence officials say Binalshibh may also have been involved in the attacks on the USS Cole and a Tunisian synagogue.
He has been sent to Guantanamo Bay, Cuba.
Mohammed Haydar Zammar
Zammar is believed to have been in Hamburg with Mohammed Atta and other members of his cell – including hijackers Marwan al-Shehhi and Ziad Jarrah.
Investigators have said that it was he who recruited them to the al-Qaeda cause, although doubts have since been cast on whether he did in fact carry out this role.
A German citizen, he was arrested in Morocco after he left Germany in the wake of the 11 September attacks. Moroccan authorities later sent him to Syria.
Syrian interrogation is reported to have provided US investigators with details about the attack and plans for more possible al-Qaeda operations, according to reports.
Ali Abdul Rahman al-Ghamdi
Described as al-Qaeda’s top leader in Saudi Arabia, Ghamdi is suspected of masterminding the deadly 2003 bombings in Riyadh.
He surrendered to the Saudi authorities shortly after the attacks. His reasons for doing so remain unclear, although it is thought his family had come under immense pressure to reveal his whereabouts.
He was born in 1974 and is said to have gained battlefield experience in Afghanistan and Chechnya. He is also believed to have been present at the beginning of the battle for the Afghan cave compound at Tora Bora in late 2001 – where Osama Bin Laden is alleged to have hidden.
Mohamedou Ould Slahi
Slahi is alleged to have played a key role in the recruitment of Atta’s cell in Hamburg.
A Mauritanian who lived in Germany through much of the 1990s, Slahi was turned over to the United States by the government of Mauritania after 11 September on suspicion of involvement in a plot to bomb Los Angeles International Airport during the 2000 millennium celebrations.
He is believed to be held in Guantanamo Bay.
In November 2002, security officials in Kuwait arrested the man thought to be a senior member of al-Qaeda.
Identified only as Mohsen F, a 21-year-old Kuwaiti national, local press said he had been plotting to blow up a hotel in the Yemeni capital, Sana’a.
In May 2006 Zacarias Moussaoui, a French citizen of Moroccan origin, was sentenced by a US court to life in prison without possibility of parole for his role in the 11 September 2001 attacks.
He had pleaded guilty a year earlier to conspiring with the 19 men who carried out the suicide hijacking attacks on New York and Washington.
The US government sought the death penalty for Moussaoui, the only person in the US charged over 9/11, but defence lawyers successfully argued for life imprisonment.
Moussaoui has lodged an appeal against the sentence. His lawyers asked the appeal court to review the trial and to reconsider a ruling that refused him leave to withdraw his guilty plea after sentencing.
Moussaoui was arrested on immigration charges at a flight simulator school in Minnesota in August 2001.
Although he was in jail at the time of the 11 September attacks, prosecutors said he told lies to allow the plot to continue. His defence said he should not be executed because he played a limited role and was mentally ill.
In 2003, Mounir al-Motassadek, a Moroccan, was the first person in the world to be convicted in connection with the 11 September attacks. But he appealed and in 2004 Germany’s Supreme Court threw the verdict out and ordered a retrial.
The court ruled he had been denied a fair trial because the US had refused his defence team access to testimony from al-Qaeda suspects in US custody.
Before the retrial in Hamburg the US justice department provided summaries from the interrogation of Binalshibh and other suspects, but did not allow them to testify.
At the retrial Motassadek was cleared of knowing about the 9/11 plot but was jailed instead for seven years for membership of a terrorist organisation.
Throughout proceedings Motassadek insisted he was innocent – that he knew nothing about the attacks, and knew the hijackers only socially.
He was released from jail in February 2006 pending appeals by both the prosecution and defence. Germany’s Federal Constitutional Court said his release did not affect his conviction.
British-born Richard Reid was sentenced to life in prison in January 2003 after being found guilty of trying to blow up an airliner with explosives hidden in his shoes.
During his trial Reid – the so-called “shoe bomber” – changed his plea to guilty on all eight charges against him and declared himself a follower of Osama Bin Laden.
Speaking during sentencing, Reid told the court: “I admit my actions… I do not apologise for my actions and I am still at war with your country.”
Reid was arrested after a disturbance on an American Airlines Paris-to-Miami flight on 22 December 2001.
Despite Reid’s pledges of support to Bin Laden, his defence team made the case that he was acting alone and was not truly affiliated with al-Qaeda.
Abd al-Rahim al-Nashiri
A Yemeni court in September 2004 sentenced Abd al-Rahim al-Nashiri to death over the bomb attack on the USS Cole, which killed 17 sailors in 2000.
However, he remains in US custody, in an undisclosed location and was tried in absentia.
The Saudi-born militant was arrested in the United Arab Emirates in October 2002 and handed over to Washington.
He was believed to have been the leader of the network’s operations in the Gulf.
Nashiri, also known as Abu Asim al-Makki, has also been linked by the US to the 1998 bombings of American embassies in Kenya and Tanzania.
After the Cole attack, he is said to have travelled to Afghanistan, escaping via Pakistan to Yemen after the US-led invasion that ousted the Taleban.
Dead or believed dead
Abu Musab al-Zarqawi
Abu Musab al-Zarqawi, a Jordanian also known as Ahmed al-Khalayleh, was killed in a US air strike on a safe house near the Iraqi city of Baquba in June 2006.
He stood accused of spearheading al-Qaeda’s campaign against the US occupation of Iraq.
In February 2004, the US military released a letter it claimed to have intercepted in which Zarqawi apparently asks al-Qaeda to help ignite a sectarian conflict in Iraq.
His name was linked to the deadly suicide bombings targeting Iraqi Shia Muslims and security services. He was also suspected of direct involvement in the kidnappings and execution of foreign workers in Iraq.
A $25m bounty was placed on his head, although some experts believe that much terrorist activity in Iraq – while inspired by him – was taking place independently of him.
US forces said in April 2005 they had come close to capturing him in Iraq.
Zarqawi was tried in absentia and sentenced to death for planning attacks in his native Jordan. Intelligence officers in Morocco and Turkey also implicated him in high-profile suicide attacks there during 2003.
He is thought to have travelled extensively after 9/11, reportedly spending time in Iran, Pakistan, Syria, Lebanon and Turkey.
Amjad Farooqi, alias Amjad Hussain, is said to have risen through the ranks of Pakistani Sunni militant groups to become a key al-Qaeda operative.
Pakistani security services allege he organised two failed assassination attempts on President Pervez Musharraf.
He was also wanted in connection with the kidnapping and killing of Wall Street Journal reporter Daniel Pearl.
He was reportedly killed in a shoot-out with security forces in southern Pakistan in September 2004.
Mohammed Atef, also known as Abu Hafez, was believed to be one of Osama Bin Laden’s most important lieutenants and the military commander of al-Qaeda.
Before joining forces with Bin Laden, Atef was an Egyptian policeman and member of Egyptian Islamic Jihad.
The US Defence Secretary, Donald Rumsfeld, said that he was believed to have been killed in the US bombing campaign in Afghanistan in November 2001.
Ali Qaed Senyan al-Harthi
Also known as Abu Ali, he is believed to be one of six al-Qaeda suspects killed by a US operation in Yemen in November 2002.
He was a prime target in the US counter-terrorism campaign because of his suspected involvement in the October 2000 bombing of the USS Cole ship in Yemen’s Aden harbour.
Abu Hazim al-Shair
US intelligence officials had identified Abu Hazim al-Shair, once one of Osama bin Laden’s bodyguards, as al-Qaeda’s new chief of operations for the Gulf states.
The 30-year-old Yemeni was believed to live in Saudi Arabia, and featured high on the list of 19 most-wanted al-Qaeda operatives in the country.
Thought to have been a key planner in the May 2003 bombings of Western residential compounds in Riyadh, he was reported to have been killed in the east of the city during in an exchange of fire with Saudi security forces in March 2004.