<a href="index.php?page=&url=http%3A%2F%2Fedition.cnn.com%2F2014%2F07%2F07%2Fworld%2Fmeast%2Firaq-crisis%2Findex.html"> </a>The U.S. military frequently announces the deaths of "key" terrorist leaders in drone strikes and special ops, but more emerge to take their places. CNN looks at some of the most wanted -- and others who have been killed. <a href="index.php?page=&url=http%3A%2F%2Fedition.cnn.com%2F2014%2F07%2F07%2Fworld%2Fmeast%2Firaq-crisis%2Findex.html">Abu Bakr al-Baghdadi, pictured, </a>is the self-proclaimed Caliph of the Islamic State in Iraq and Syria (ISIS).
Abu Bakr al-Baghdadi —
The U.S. military frequently announces the deaths of "key" terrorist leaders in drone strikes and special ops, but more emerge to take their places. CNN looks at some of the most wanted -- and others who have been killed. Abu Bakr al-Baghdadi, pictured, is the self-proclaimed Caliph of the Islamic State in Iraq and Syria (ISIS).
AL-FURQAN MEDIA/AFP/Getty Images
<a href="index.php?page=&url=http%3A%2F%2Fedition.cnn.com%2F2014%2F05%2F07%2Fworld%2Fafrica%2Fabubakar-shekau-profile%2Findex.html">Abubakar Shekau</a> is believed to the be the leader of Boko Haram, based in Nigeria. He appears in videotaped messages from the militant group.
Abubakar Shekau —
Abubakar Shekau is believed to the be the leader of Boko Haram, based in Nigeria. He appears in videotaped messages from the militant group.
BOKO HARAM/AFP
<a href="index.php?page=&url=http%3A%2F%2Fedition.cnn.com%2F2011%2FUS%2F06%2F16%2Fus.zawahiri%2Findex.html">Ayman al-Zawahiri </a>took over the leadership of al Qaeda from Osama bin Laden, who was killed in a U.S. operation in 2011.
Ayman al-Zawahiri —
Ayman al-Zawahiri took over the leadership of al Qaeda from Osama bin Laden, who was killed in a U.S. operation in 2011.
Site Intelligence Group/AFP/Getty Images
<a href="index.php?page=&url=http%3A%2F%2Fedition.cnn.com%2F2014%2F11%2F06%2Fworld%2Fmeast%2Fsyria-strike-bomb-maker%2Findex.html">Ibrahim al-Asiri</a> is thought to be the chief bomb maker for al Qaeda in the Arabian Peninsula (AQAP), and he is also thought to have trained bomb-makers from his hideout in a remote corner of Yemen.
Ibrahim Hassan al-Asiri —
Ibrahim al-Asiri is thought to be the chief bomb maker for al Qaeda in the Arabian Peninsula (AQAP), and he is also thought to have trained bomb-makers from his hideout in a remote corner of Yemen.
Saudi Interior Ministry/Reuters/Landov
<a href="index.php?page=&url=http%3A%2F%2Fedition.cnn.com%2F2015%2F07%2F24%2Fworld%2Fafghanistan-al-qaeda-commander-killed%2Findex.html">Abu Khalil al-Sudani,</a> a senior figure in al Qaeda in Afghanistan, was killed on July 11, according to the U.S. military. It said al-Sudani had headed al Qaeda's suicide and explosive operations.
Abu Khalil al-Sudani (killed on July 11, 2015) —
Abu Khalil al-Sudani, a senior figure in al Qaeda in Afghanistan, was killed on July 11, according to the U.S. military. It said al-Sudani had headed al Qaeda's suicide and explosive operations.
CNN
<a href="index.php?page=&url=http%3A%2F%2Fedition.cnn.com%2Fvideos%2Fworld%2F2015%2F07%2F22%2Fsyria-air-strike-khorasan-terror-al-qaeda-drone-leader-starr.cnn%2Fvideo%2Fplaylists%2Fal-qaeda%2F">Muhsin al-Fadhli</a> was the alleged leader of the Khorasan Group -- an al Qaeda offshoot in Syria. The Pentagon said the Kuwaiti-born jihadi was killed in a targeted strike in July.
Muhsin al-Fadhli (killed on July 8, 2015) —
Muhsin al-Fadhli was the alleged leader of the Khorasan Group -- an al Qaeda offshoot in Syria. The Pentagon said the Kuwaiti-born jihadi was killed in a targeted strike in July.
AL-WATAN NEWSPAPER/AFP/Getty Images
<a href="index.php?page=&url=http%3A%2F%2Fedition.cnn.com%2F2015%2F07%2F02%2Fmiddleeast%2Fisis-leader-killed%2Findex.html">Senior ISIS leader Tariq al-Harzi </a>-- known as the "emir of suicide bombers" -- was killed by a coalition airstrike in Syria, according to U.S. officials. Al-Harzi played a key logistical role for ISIS, overseeing efforts to get jihadists and weapons into Iraq and Syria, according to officials in the U.S. and North Africa.
Tariq al-Harzi (killed on June 16, 2015) —
Senior ISIS leader Tariq al-Harzi -- known as the "emir of suicide bombers" -- was killed by a coalition airstrike in Syria, according to U.S. officials. Al-Harzi played a key logistical role for ISIS, overseeing efforts to get jihadists and weapons into Iraq and Syria, according to officials in the U.S. and North Africa.
U.S. State Department
Nasir al-Wuhayshi was leader of al Qaeda in the Arabian Peninsula (AQAP). Killed in June, <a href="index.php?page=&url=http%3A%2F%2Fedition.cnn.com%2F2015%2F06%2F16%2Fmiddleeast%2Fwuhayshi-death-impact%2F">he was described as</a> "one of the last al Qaeda heavyweights, a fighter's fighter."
Nasir al-Wuhayshi (killed on June 12, 2015) —
Nasir al-Wuhayshi was leader of al Qaeda in the Arabian Peninsula (AQAP). Killed in June, he was described as "one of the last al Qaeda heavyweights, a fighter's fighter."
AFP/Getty Images
The killing of Yemeni-American cleric Anwar al-Awlaki, in a drone strike in September 2011, deprived al Qaeda of its most effective propagandist, according to CNN's Tim Lister.
Anwar al-Awlaki (Killed in September 2011) —
The killing of Yemeni-American cleric Anwar al-Awlaki, in a drone strike in September 2011, deprived al Qaeda of its most effective propagandist, according to CNN's Tim Lister.
Tracy Woodward/The Washington Post/Getty Images
<a href="index.php?page=&url=http%3A%2F%2Fedition.cnn.com%2F2013%2F05%2F01%2Fus%2Fgallery%2Fosama-bin-laden-death%2Findex.html">The 2011 death of al Qaeda leader Osama bin Laden </a>was symbolically important. But other terrorist leaders have followed in his wake.
Osama bin Laden (killed in May 2011) —
The 2011 death of al Qaeda leader Osama bin Laden was symbolically important. But other terrorist leaders have followed in his wake.
Getty Images
U.S. officials believed<a href="index.php?page=&url=http%3A%2F%2Fedition.cnn.com%2F2008%2FWORLD%2Fasiapcf%2F08%2F03%2Fterrorist.killed%2Findex.html"> al Qaeda's master bomb-maker, Abu Khabab al-Masri,</a> tutored dozens of apprentices at his camp in Afghanistan before his death in 2008.
Abu Khabab al-Masri (killed in July 2008) —
U.S. officials believed al Qaeda's master bomb-maker, Abu Khabab al-Masri, tutored dozens of apprentices at his camp in Afghanistan before his death in 2008.
U.S. State Department
The<a href="index.php?page=&url=http%3A%2F%2Fedition.cnn.com%2F2006%2FWORLD%2Fmeast%2F06%2F08%2Firaq.al.zarqawi%2F"> killing of Abu Musab al-Zarqawi </a>in a 2006 U.S. airstrike was seen at the time as a body blow to the group he led -- al Qaeda in Iraq. But by then he had laid the foundations of a group that would eventually morph into and inspire ISIS.
Abu Musab al-Zarqawi (Killed in June 2006) —
The killing of Abu Musab al-Zarqawi in a 2006 U.S. airstrike was seen at the time as a body blow to the group he led -- al Qaeda in Iraq. But by then he had laid the foundations of a group that would eventually morph into and inspire ISIS.
DOD/Getty Images