He died Thursday as rebels secured Sirte, Gadhafi's hometown. He was 73. The death followed months of turmoil during the so-called Arab Spring that has seen unrest across the Middle East and the ouster of Egypt's and Tunisia's presidents.
Gadhafi was a thorn in the West's side for decades. After the fall of Saddam Hussein in Iraq in 2003, Gadhafi renounced his country's nuclear program and offered $2.7 billion to the families of victims of the Lockerbie, Scotland, bombing that killed 259 people aboard Pan Am Flight 103, as well as 11 on the ground. His prime minister said Gadhafi was attempting to buy peace with the West.
In the years following the bloodless coup that catapulted him to power in 1969, Gadhafi became one of the Arab world's most controversial figures. Among other things, he commissioned international "hit squads" to eliminate Libyan opponents living outside the North African country.
Some sources charged he sent a special hit squad, headed by the international terrorist Carlos the Jackal, to the United States to assassinate President Ronald Reagan and other senior U.S. government officials.
Reagan called Gadhafi a "madman" and "the most dangerous man in the world."
The U.S. CIA personality profile of Gadhafi portrayed him as a "messianic paranoid who will never back down in a public confrontation."
In February 1985, speaking by satellite to a Nation of Islam International Savior's Day Convention in Chicago, Gadhafi said he stood ready to arm a black army in the United States to destroy "white America" and set up an independent state.
In Washington, a White House spokesman charged Gadhafi was using racism to encourage "sedition" in urging black soldiers to desert the U.S. armed forces.
At 2 a.m. local time on April 15, 1986, U.S. warplanes struck Libyan targets in Tripoli and Benghazi, killing a score of people including Gadhafi's 15-month-old adopted daughter. The attack, announced by Reagan in a TV address moments after it was carried out, was the biggest U.S. airstrike since the Vietnam War.
Secretary of State George Shultz said Libya had been preparing attacks on up to 30 U.S. embassies worldwide.
Gadhafi was stunned.
In an interview with United Press International in Tripoli on June 19, 1986, his first with a Western reporter following the April 15 raid, Gadhafi said he was at home when U.S. planes bombed Tripoli and he helped rescue his wife and children while "the house was coming down around us."
Gadhafi accused Reagan, who ordered the attack on Libya in retaliation for Gadhafi's alleged support of terrorism, of trying to kill him.
Gadhafi said reconciliation between Libya and the United States was impossible so long as Reagan was in the White House.
"I have nothing to say to him because he is mad. He is foolish. He is an Israeli dog," Gadhafi said. Arab fury over the attack won him a brief respite, but he was increasingly isolated among his own Muslim brethren and confronted by enemies among his own people at home and abroad.
A strict observer of the Koran, the Muslim holy book, Gadhafi outlawed drinking, brothels and gambling casinos when he came to power in an effort to "Arabize" Libya and rid it of Western influences.
Gadhafi called his social and political philosophy an alternative to "capitalist materialism and communist atheism." He vowed in his early years of power to transform his country into a "society of equality and justice." He promoted public works projects, increased minimum wages and dismissed hundreds of corrupt civil servants.
Gadhafi, who Egyptian President Anwar Sadat called "an infantile nitwit," once offered Sadat's successor, Hosni Mubarak, $5 billion if he would tear up the Camp David accord with Israel. Mubarak refused.
Gadhafi broke with Palestine Liberation Organization Chairman Yasser Arafat when Arafat rejected his proposal to blow up the Suez Canal.
The Libyan leader further offended Arafat by openly suggesting, during the Israeli siege against the PLO in Beirut in 1982, that Arafat do "the honorable thing and commit suicide."
Gadhafi once offered cash to the outlawed Irish Republican Army if its members would renounce Roman Catholicism for Islam.
Gadhafi's adventures in international terrorism reportedly included plots against the president of the United States, the pope, the king of Saudi Arabia and a string of nations.
Gadhafi was born on an unknown date in 1938 -- some authorities say 1941 -- in a goatskin tent in the Libyan desert to a Bedouin farmer who raised barley and traded horses and camels.
His father scrimped to educate his son. At the Benghazi Military Academy his intense political activity made him a dominant figure.
On Sept. 1, 1969, Gadhafi led a bloodless coup that deposed King Idris, who Gadhafi despised as corrupt and subservient to the United States and Britain.
Twelve days later, the 31-year-old Gadhafi became president of the Revolutionary Command Council.
His first years in power were remarkable for his unrelenting though unsuccessful attempts to merge Libya with other Arab countries, first with Egypt and Syria.
He sought to unite Libya with Tunisia in 1974 and then with Chad in 1981.
When these efforts failed, he sometimes attacked the leaders of those countries and appealed directly to the people, offering them material aid in overthrowing their governments.
Libya was implicated in coup attempts in Egypt in April 1974 and in Sudan a month later. He openly supported an abortive coup against King Hassan II of Morocco in 1971.
Gadhafi sent troops into Chad in December 1979 shortly before announcing plans for the two countries to unite.
Having closed American and British military bases in Libya in 1970, Gadhafi gave the Soviet Union access to his oil fields in return for weapons in 1972.
On Nov. 18, 1984, Mubarak accused Gadhafi of financing death squads to kill Arab and Western European leaders, including U.K. Prime Minister Margaret Thatcher and French President Francois Mitterrand.
Gadhafi inherited some of the richest and finest oil reserves in the world.
If oil was Libya's No. 1 business, former CIA Director William Casey said, then "training guerrillas and terrorists is the second-largest industry there."
CIA sources said Libya supported more than 25 terrorist and guerrilla training bases. The ranks included Palestinians, Americans, Syrians, Yemenis and Iranians, some of them trained in Moscow, as well as advisers from Britain, France and the Soviet Union.
Gadhafi and his wife Safiya had seven children.