Final answer:
Saddam Hussein was the Iraqi dictator who brutalized his own people and engaged in mass executions. He was not affiliated with Al Qaeda, despite having a reputation for oppression and terrorism. Hussein was overthrown and executed after the U.S.-led invasion of Iraq in 2003.
Step-by-step explanation:
The leader of Iraq who brutalized his people, harbored terrorist cells, and ordered mass executions of citizens was Saddam Hussein. Hussein ruled Iraq from 1979 to 2003 and during his regime, he was known for using chemical weapons against his own people, particularly the Kurds, and during the Iran-Iraq War.
His government was secular Ba'athist with a strong hand, promoting Arab nationalism, but brutally suppressing political dissent and any ethnic uprisings, as seen in his attacks on civilian Kurdish populations. Although associated with oppression and terror, it is also to be noted that accusations of collaboration with Al Qaeda are not substantiated, as Saddam Hussein's ideology clashed with that of Osama bin Laden's Islamist fundamentalism.
After Saddam Hussein's invasion of Kuwait in 1990, the United Nations, led by the United States, engaged in the First Persian Gulf War that pushed Iraqi forces out of Kuwait. Saddam Hussein's use of weapons of mass destruction was also among the reasons cited for the US-led invasion of Iraq in 2003, known as Operation Iraqi Freedom. This invasion resulted in Hussein being ousted from power, captured, and eventually executed by the Iraqi government.