Mayor Rudy Giuliani: Giuliani was New York City's 107th Mayor. During the attacks, he was trapped inside a building on Barclays Street, near the towers, with the police and fire commissioners.
Giuliani was the target of criticism for ignoring terrorism threats between the World Trade Center 1993 car bombings and the attacks of September 11th: the lack of preparedness on the part of the Giuliani administration is sometimes blamed for the deaths of the first responders.
After the attacks, Giuliani made himself very visible to the media, publically rejecting a gift of $10 million from Saudi Prince Alwaleed bin Talal, after he suggested that the US "should re-examine its policies in the Middle East." His approval ratings shot up to 79 percent from 36 percent, Oprah Winfrey anointed him "America's Mayor," and he got closely involved with recovery and rebuilding efforts.
In 2002, after leaving office, Giuliani received an OBE from Queen Elizabeth. Since the attacks he has taken criticism for downplaying the poor air quality in New York after the towers collapsed. He campaigned briefly for president in 2008, and has since founded Giuliani Partners LLC, a security consulting business and joined the law firm Bracewell & Giuliani LLP.
Governor George Pataki: Pataki was the 53rd governor of New York. He was in his third term as governor when the attacks happened.
He said in an interview on the 9th anniversary of the attacks that, "I saw the second plane hit and knew right away that we were being attacked and I started to take action," and that just hours after the attack he was "walking the streets of Manhattan doing his best to console a city in shock."
Pataki's role in the days and months after 9/11 was greatly overshadowed by Giulani's role, and he took some criticism from Andrew Cuomo, who at the time was running for governor, that "[Pataki] was a great assistant to the leader [Giuliani], but he was not a leader."
After leaving office, Pataki joined the law firm Chadbourne & Parke, and in 2007 was part of the U.S. delegation at the U.N. General Assembly. After some speculation, he announced he would not throw his hat into the 2012 presidential ring.
NYPD Police Commissioner Bernard Kerik: Kerik served as police commissioner for a little over a year under Giuliani, leaving his post when Giuliani left office on December 31, 2001.
During the attacks, Kerik told the New York Daily News he felt angry. "It's not often in this job that you don't have control over what's going on," he said. Kerik was in his office when the first plane hit, and was with Giuliani on Barclay Street, close to the towers when the second plane hit.
The 9/11 attacks exposed some large holes in the command procedures of the FDNY and NYPD; too many police and firemen decided to go straight into the buildings instead of to the surrounding streets as they were directed.
After 9/11 and leaving the NYPD, Kerik was briefly appointed by President George W. Bush as Interim Interior Minister in Iraq, and worked as a Senior VP for Giuliani Partners. In December of 2004, President Bush nominated him to be the second Secretary of Homeland Security, but withdrew his acceptance of the nomination after facing allegations of hiring illegal immigrants in his household. Eventually, further allegations came out, accusing Kerik of, among other things, insider trading, sexual harassment, and having connections to organized crime.
In June 2006, Kerik pleaded guilty to two ethics violations while serving as police commissioner, and in 2007 he was indicted by a grand jury for tax fraud, conspiracy, and making false statements in his testimony to the White House when he was nominated for Secretary of Homeland Security. He is currently incarcerated and serving a four-year sentence at the Federal Correctional Institution in Maryland, acroding to ABCNews.
FDNY Fire Commissioner, Thomas Von Essen: Von Essen was the 30th FDNY Commissioner. He was appointed by Giuliani in 1996, and retired when Giuliani left office on December 31, 2001.
Von Essen is often accused of making the 9/11 situation worse: one reason was the FDNY had recently purchased new radios that were not properly field tested, and possibly contributed to the breakdown in communications between emergency teams operating on the day.
Von Essen released a book in August of 2002, called "Strong of Heart: Life and Death in the Fire Department of New York." The book covered his career as an FDNY firefighter, as well as what happened on the day of the attacks. It received mostly positive reviews, although the New York Times book review noted that Von Essen glossed over much of the chaos and lack of coordination between the NYPD and the FDNY.
In 2002, he received an honorary OBE from Queen Elizabeth alongside Mayor Giuliani. Von Essen worked with Giuliani after leaving the FDNY, as a Senior VP at Giuliani Partners and then as CEO of Giuliani-Von Essen LLC . He is also a Fire and Life Safety Consultant for the Allbaugh International Group, LLC, and teaches as an adjunct professor at New Jersey City University College of Professional Studies.
President George W. Bush: The 43rd U.S. President, George W. Bush was in a classroom in Florida reading the story "The Pet Goat" with a group of children when his Chief of Staff Andrew Card informed him of the attacks. He visited the site on September 14th, and in October, launched Operation Enduring Freedom in Afghanistan, the first part of the War on Terror.
Bush has kept a low profile since leaving office, mostly appearing at events in his home state, Texas. He has defended his administration's use of waterboarding and other "enhanced interrogation techniques" to question suspected terrorists, as well as the 2003 decision to invade Iraq as part of the War on Terror, two of the most contentious points of his presidency.
Vice President Dick Cheney: Former Vice President Richard "Dick" Cheney remains one of the most controversial figures of 9/11 and its aftermath. He was one of the primary movers behind the U.S. invasion of Iraq in 2003 and continued to defend the administration's decision to invade after the 9/11 commission determined that Iraq had played no part in the attacks.
He was also one of the central figures of the Valerie Plame scandal, wherein a CIA agent's cover was blown, after her husband, former Ambassador Joe Wilson, wrote a series of articles that claimed the Bush administration has purposefully "manipulated intelligence" to find a reason to invade Iraq.
Since leaving the vice presidency, Cheney has been living in Virginia, and has been an active political commentator.
Osama Bin Laden: The mastermind behind the 9/11 attacks and the founder of Al-Qaeda did not fully claim responsibility for the attacks until 2004, when he released a video through Al Jazeera claiming that, "The events that affected me directly were that of 1982 and the events that followed-when America allowed the Israelis to invade Lebanon...As I watched the destroyed towers in Lebanon, it occurred to me punish the unjust the same way: to destroy towers in America so it could taste some of what we are tasting and to stop killing our children and women."
Bin Laden escaped U.S. clutches in late 2001, and was thought to be hiding in Afghanistan, but raids and missions failed to produce him. The U.S. continued to received conflicting reports as to his wearabouts even through 2011, when another Al-Jazeera report claimed that Bin Laden had been captured in Afghanistan.
Bin Laden was eventually found living in relative comfort in Abbottabad, Pakistan, and was killed on May 2, 2011.
Khalid Sheikh Mohammed: Born in Kuwait in 1964 or 1965, Mohammed is alleged to be "one of the principal architects of the 9/11 attacks." He was captured in March 2003 in Pakistan, and has been in the prison at Guantanamo Bay, Cuba, ever since.
In March 2007, he confessed to his role in the 9/11 attacks, saying, "I was responsible for the 9/11 operation, from A to Z," CNN reported. He also confessed to a role in 29 other operations, including the 1993 World Trade Center car bombing, and the Lockerbie bombing. He is still in Gitmo, and is still undergoing trial by military commission for war crimes.
The 20th hijacker, Ramzi Bin al-Shibh: Shibh, another key player in the September 11 attacks, is accused of wiring money and passing information between the hijackers and al-Qaeda leaders. He was originally supposed to be one of the hijackers on the planes, but failed to obtain an entrance visa to the U.S. He is sometimes called the 20th hijacker.
He was captured in Pakistan on September 11, 2002, and after being held in Morocco, was transferred to Guantanamo Bay in September 2006. He is classified as one of the "high-value" detainees, along with Khalid Sheikh Mohammed. As of May 2011, he announced that he was ready to stand trial and wants to represent himself before the military commissions.
Zacarias Moussaoui: Moussaoui was the first suspected terrorist to be tried in connection with the 9/11 attacks, and the only suspect to have been tried in the United States. Born in France, Moussaoui is also often called the 20th hijacker of the four planes, but prosecutors could not effectively link him to the 19 other hijackers. He took flying lessons at the Airman Flight School in Oklahoma, the same school at which hijackers Mohamed Atta and Marwan al-Shehhi took lessons. His flight instructor was suspicious about Moussaoui's intentions and called the FBI.
He was arrested on August 16, 2001, before the attacks took place, on charges of immigration violation, and in December of 2011 was indicted on charges of conspiracy to commit terrorism, to use weapons of mass destruction, and to murder US employees, among other charges.
He is currently serving a life sentence without parole at the Federal ADX Supermax Prison in Florence, Colorado. He has since claimed that he was not involved in the September 11 attacks.