Moammar Gadhafi is an eccentric leader who came to power in a bloodless coup in 1969 as the 27-year-old captain who deposed a king. He fancied himself the Arab world's answer to Mao or Castro, vowing to bring "Islamic socialism" to Libya.
Since his rise to power 42 years ago Gadhafi has been an erratic player on the international stage, continually switching policies and allegiances throughout the decades.
Long before Saddam Hussein and Osama bin Laden ever made America's most wanted list, Gadhafi, 68, was the world's top sponsor of international terrorism. President Ronald Reagan called him the "mad dog of the Middle East" and said that Gadhafi's goal was "a world revolution, a Muslim fundamentalist revolution."
In retaliation for Libya's bombing of a West German disco that killed two American soldiers in 1986, Reagan ordered an air strike on Gadhafi's compound. Gadhafi survived the strike but his adopted baby daughter died.
The United States and Libya would be at odds again in 1988 after the United States determined that Libyan agents were behind the bombing of Pan Am flight 103 over Lockerbie, Scotland. The bombing killed 270 people, including 189 Americans.
The terrorist attack resulted in the United States and the United Nations imposing strict sanctions on Libya. One year later, Libya would be blamed for another terrorist attack, the 1989 bombing of a French airliner over Niger in West Africa. That attack killed 170 people of 17 nationalities.
A frequent adversary of the United States through the '70s, '80s and '90s, Gadhafi has worked to repair his relationship with America in the past decade. In 1999, he handed over the two Libyans charged in the Lockerbie bombing and in 2001 he was one of the first Arab leaders to issue a statement of condolences to the United States after 9/11.
"It is human duty to show sympathy with the American people and be with them in these horrifying and awesome events which are bound to awaken human conscience," he said.
The restoration of normal diplomatic relations with the United States has taken years, ABC News' Chirstiane Amanpour said.
"Gadhafi has not been a reliable partner by any stretch of the imagination over the last several decades," she said. "There were ties cut between the United States and Libya for many, many years, only resumed back in 2009 and only after the war with Iraq. After which Gadhafi decided to put on the table and basically hand over any plans for any weapons of mass destruction."
Gadhafi has also been a fierce critic of al Qaeda, calling it a common enemy that must be fought. Although he has been hesitant to accept full responsibility for the bombing of Pan Am 103 and the French airliner, he has agreed to pay out more than $2.7 billion in damages to the victims' families.
More recently, Gadhafi has come under fire from the international community after welcoming the convicted Lockerbie bomber back to Libya as a hero when he was released from prison on compassionate grounds.
Today, the man who has controlled the North African nation with his own style is fighting his own people to remain in power.
Timeline: Gadhafi's Reign
1942: Gadhafi is born to a Bedouin father in the central Libyan desert. His father was once jailed for opposing Italy's occupation from 1911 to 1941.
1969: As a 27-year-old captain, Gadhafi becomes Libya's undisputed ruler by overthrowing the monarchy in a largely peaceful coup.
Timeline: Gadhafi's Reign
1970s: Gadhafi makes changes to establish a socialist system. He nationalizes businesses, expels 20,000 Italians and closes a U.S. air base.
1980s: Gadhafi supports groups the United States considers terrorists, including the IRA and radical Palestinian factions. In 1986, U.S. jets bomb Libya after it is found responsible for the bombing of a Berlin disco frequented by U.S. troops.
1988: Suspected Libyan agents bomb Pan Am Flight 103 over Lockerbie, Scotland. The bombing killed 270 people, including 189 Americans.
1989: Libya is blamed for the bombing of a French airline over Niger. The attack killed 170 people.
1999: Gadhafi hands over two Libyans charged in the Lockerbie bombing.
2001: A Scottish court convicts Abdel Baset al-Megrahi of the Lockerbie bombing and sentences him to life in prison. The other suspect is acquitted.
2003: Libya takes responsibility for the Lockerbie bombing and agrees to pay up to $10 million to the relatives of each victim. It also announces that it will dismantle all weapons of mass destruction.
2009: Days before Gadhafi celebrates 40 years in power, he angers the international community by welcoming al-Megrahi home as a hero. Al-Megrahi was convicted of the Lockerbie bombing, but released on compassionate grounds because he was purportedly dying of cancer.
Feb. 21, 2011: Gadhafi's regime begins to falter. Diplomats and the justice minister resign, while air force pilots defect. Protesters claim control of Benghazi after some army units side with them.
The Associated Press contributed to this report.