Gadhafi became an advocate of Arab and African unity, and openly declared his vision for a "United States of Africa." But his relationship with the western world was strained and Gadhafi instead became known as the top sponsor of terrorism and for harboring international fugitives.
At the height of his ability to threaten terrorism, President Ronald Reagan dubbed Gadhafi the "mad dog of the Middle East."
He was accused of backing the 1986 bombing of a Berlin disco popular with American soldiers, reportedly funding the hijacking of the cruise ship Achille Lauro in 1985, and the 1988 bombing of Pan Am Flight 103, which resulted in the U.N. and United States imposing sanctions on Libya.
For years, Gadhafi refused to take responsibility for the bombing, but that changed in 2003 when he acknowledged his role and tried to make amends.
Western nations established diplomatic relations with Libya in 2003 after Gadhafi agreed to give up weapons of mass destruction.
The eccentric leader, who amassed power and wealth by controlling the nation's oil industry, held the title of being the longest-serving leader in Africa and the Arab world.
Over the years, Gadhafi earned an international reputation for his outlandish apparel and much-ridiculed phobias and proclivities.
In U.S. diplomatic cables recently released by WikiLeaks, Gadhafi was described as a "mercurial and eccentric figure who suffers from severe phobias, enjoys flamenco dancing and horse racing, acts on whims and irritates friends and enemies alike."
He was "obsessively dependent on a small core of trusted personnel," especially his longtime Ukrainian nurse Galyna, who has been described as a "voluptuous blonde," according to the cables.
Among his other unusual behaviors, the Libyan leader reportedly feared flying over water, didn't like staying on upper floors and traveled with a "pistol packing' posse" of female bodyguards.
ABC News' Luis Martinez contributed to this report.