It's been 12 years since the Sept. 11, 2001 terror attacks and though al Qaeda's leader, Osama bin Laden was killed more than two years ago, the group and its terrorist affiliates remain - populated in part by high-profile recruits straight from the American homeland.

Below are five men, considered U.S. persons and alleged supporters of terrorism wanted so badly by the U.S. government that a reward of $21 million has been offered in total for information leading to their arrest or conviction. Federal authorities consider all of these men "armed and dangerous."

FBI/AP Graphics

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Omar Shafik Hammami: $5 Million

Omar Hammami, known as the rapping jihadist for a series of videos in which he rhymes about battling infidels, was born in Alabama but traveled to Somalia years ago to fight alongside al-Shabaab, an al Qaeda-affiliated terror group there.

Known to his terrorist comrades as Abu Mansoor al-Amriki, or "the American," Hammami is accused by the U.S. government of being a propagandist for al-Shabaab and, at times, a military leader in the organization. However, a curiously public spat between Hammami and al-Shabaab's local leadership has put his status in the organization into question.

Hammami is wanted by the U.S. government for allegedly providing material support to terrorists.

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Adam Yahiye Gadahn: $1 Million

Born Adam Pearlman, Adam Gadahn is one of the most high-profile members of al Qaeda. He left his home in California for Pakistan more than a decade ago, seeking out the terror group.

The 35-year-old has served as a spokesman for al Qaeda in the past and in 2010 released a video message to President Obama, ridiculing him for a drop in popularity.

Documents recovered from bin Laden's Pakistani compound show that Gadahn was a "breakout personality" who plays a "significant role" in al Qaeda for his media skills, according to West Point's Combating Terrorism Center.

He is wanted for "treason and [providing] material support to al Qaeda," according to the FBI.

Jehad Serwan Mostafa: $5 Million

In March 2013, when Hammami was added to the State Department's Rewards for Justice Program, so was Jehad Mostafa.

Mostafa, a former resident of California, at the time was also believed to be in Somalia where authorities say he "served as a media expert and leader of foreign fighters for al-Shabaab." He is formally accused of a number of terrorism related crimes, including providing material support to terrorists.

Adnan G. El Shukrijumah: $5 Million

Adnan El Shukrijumah, an asthmatic native of Saudi Arabia but considered a U.S. person by the government after living in America for years, is accused of playing a role in a plot to attack the New York City's subway system in 2009.

U.S. authorities believe the plot was hatched by senior al Qaeda leadership in Pakistan and El Shukrijumah is "thought to have served as one of the leaders of al Qaeda's external operations program," according to the FBI.

Jaber A. Elbaneh: $5 Million

Jaber Elbaneh was born in Yemen but hold dual citizenship with the U.S. He lived in New York and the FBI's Wanted poster for him says that he worked for a time as a salesman and a taxi driver.

He also allegedly provided material support to al Qaeda and was indicted in absentia as early as 2003. He was reported to have been associated with the Lackawanna Six, a group of terrorists arrested in 2002 after returning to the U.S. from an Afghan terror training camp, but Elbaneh did not return to the U.S. with the others and instead went to Yemen.

Elbaneh, who The New York Times reported briefly worked in a cheese factory in the U.S., has been in and out of prison in Yemen but the country repeatedly refused to extradite him to the U.S. to face charges.

On each of the wanted posters, the FBI asks that anyone with information relating to the suspects contact their local FBI field office or the closest U.S. embassy or consulate.