On the morning of September 11, 2001, 19 terrorists from the Islamist militant group al-Qaeda hijacked four passenger jets. The terrorists went on to pilot the aircrafts in a series of attacks that would end up claiming the lives of 3,000 people.

Much has been learned about al-Qaeda since that sad day in 2001, including information about the hierarchy of the group that masterminded the attacks. As a result, al-Qaeda underwent some dramatic transformations from assaults on the group's power base in Afghanistan to many of its leaders being captured or killed.

A recent report by CNN's Peter Bergen revealed that 16 key al-Qaeda operatives were killed or captured in Pakistan during the George W. Bush presidency. Since then, CIA drone strikes and other top-secret missions have killed 15 of the most important players in al-Qaeda under the Obama presidency.

The latter includes the widely publicized Navy SEAL Team 6 mission that is responsible for the killing of longtime al-Qaeda leader Osama Bin Laden.

While the formation of leaders in the infamous militant group has most definitely shifted over the years, take a look at al-Qaeda's leadership, 11 years after 9/11. Click "start" to see who's still in power and who is powerless.