It is the blackest of blacklists: names of the top Al Qaeda terrorist leaders that the United States wants dead or captured.

Some are almost universally known — there's Usama bin Laden, of course, and his top deputy, Ayman al-Zawahri. Others are publicly identified among the FBI's most wanted terrorists, or in other U.N. or U.S. government lists and documents, but few details are provided.

Still other senior lieutenants are known only to U.S. intelligence and military officials.

Get them, and you hurt Al Qaeda, U.S. officials and experts say.

"It disrupts the channels of communications. It disrupts the chain of command," said Stan Bedlington, a retired senior analyst from the CIA's counterterrorism center. "But the cells on the ground are allowed a certain freedom to operate. We can expect some of the cells will continue to operate."

At least three lieutenants are dead, including Mohammed Atef, an Egyptian who was among bin Laden's top aides, killed in an airstrike near Kabul. Two more high-ranking Egyptians, Tariq Anwar al-Sayyid Ahmad and Muhammad Salah, were killed in another strike near Khowst.

Many of the rest are thought to be in Afghanistan, although some, if they're still alive, may have escaped to Pakistan or elsewhere.

Many of the names are code names. Here are some of the most wanted:

• Ayman al-Zawahri, 50, believed to be bin Laden's spiritual adviser and doctor, provided the ideology that drives Al Qaeda, just as Atef provided the operational leadership before he was killed. The two Egyptians became bin Laden's top lieutenants when Egyptian Islamic Jihad merged with al-Qaida in 1998.

In videotapes of bin Laden released since Sept. 11, al-Zawahri has appeared at bin Laden's side. His wife and children were reported killed in a U.S. airstrike in late November or early December.

He has been indicted in the United States for his role in the bombings of two U.S. embassies in Africa, spent three years in prison for a background role in the 1981 assassination of Egyptian President Anwar Sadat and was sentenced to death in Egypt in absentia for his activities with the Islamic Jihad group in the 1990s.

• Shaihk Saiid, also known as Sa'd al-Sharif and Mustafa Ahmad al-Hisawi. A Saudi, Saiid, 33, is bin Laden's brother-in-law and financial chief. Saiid has been with bin Laden since his time in Sudan.

Saiid allegedly wired money to Atta in preparation for the Sept. 11 attacks, according to court documents.

• Abu Zubaydah, also known as Zain al-Abidin Muhammad Husain and Abd Al-Hadi Al-Wahab, is bin Laden's senior field commander. Zubaydah, 30, is believed to have been born in Saudi Arabia but has strong ties in Palestine and Jordan.

He's been sentenced to death in Jordan and is believed connected to many of Al Qaeda's operations against U.S. interests.

• Saif al-Adel, also known as Muhamad Ibrahim Makkawi and Ibrahim al-Madani. Al-Adel, an Egyptian in his late 30s, is bin Laden's security chief. He's believed to be taking over many of Atef's duties in Al Qaeda. He's wanted in connection with the embassy bombings.

• Abu Mohammed al-Masri, frequently known as Abdullah Ahmed Abdullah. Also an Egyptian in his late 30s, al-Masri ran bin Laden's training camps in Afghanistan, including the al-Farooq camp near Kandahar. He is also wanted in the embassy bombings.

• Sulaiman Abu Ghaith, Al Qaeda's nominal spokesman, is a Kuwaiti believed to be in his mid-30s. A former high school religion teacher, he left Kuwait in 2000. He was stripped of Kuwaiti citizenship after casting his lot with Al Qaeda. Bin Laden is seen poking fun at him in the videotape released this week.

• Abd al-Rahim al-Nashiri, also known as Omar Muhammad al-Harazi and Abu Bilal al-Makki, is a Saudi who has planned attacks against U.S. interests, according to a U.S. official, speaking on the condition of anonymity.

• Abu Basir al-Yamani, a Yemeni and bin Laden aide.

• Thirwat Salah Shihata, 41, an Egyptian, is the second-in-command to al-Zawahri in the Egyptian Islamic Jihad. He's been twice sentenced to death in absentia in Egypt for terrorist activities.

In addition, some leaders of terrorist groups affiliated with Al Qaeda have drawn the attention of U.S. authorities.

They include:

• Tohir Yuldashev, leader of the Islamic Movement of Uzbekistan.

• Taha Musa, a leader within el-Gamaa el-Islamiya in Egypt.

• Khadafi Janjalani, leader of Abu Sayyaf in the Philippines and Malaysia.

• Farooq Kashmiri, leader of Harakut ul-Mujahidin, fighting Indian control over Kashmir.

• Professor Hafiz Mohammed Saeed, leader of Lashkar-e-Tayyiba, also opposing India in Kashmir.

• Maulana Masood Azhar, leader of Jaish-e-Mohammed, another anti-Indian group in Kashmir.

• Hassan Hattab, leader of the Salafist Group for Call and Combat, in Algeria.

• Antar Zouabri, nominal leader of the Armed Islamic Group in Algeria.

• Abu Hamzu al-Masri, leader of the Islamic Army of Aden in Yemen.

• Shamil Basayev and Omar Ibn al Khattab, rebels in Chechnya with ties to al-Qaida.