Abdelbeset Ali Mohmed al Megrahi, the Libyan intelligence officer convicted in the bombing of Pan Am Flight 103 over Scotland in 1988, has died in Libya, according to media reports.
He died at home after a battle with cancer, his brother told Reuters news agency.
Al Megrahi was freed from a prison in Scotland in 2009 after serving eight years of a life sentence for blowing up the Pan Am 747, killing all 259 on board and 11 in the town of Lockerbie below.
Doctors who had been treating him for prostate cancer gave him just three months to live, and he was released on compassionate grounds.
He received a hero's welcome upon his return to Libya, enraging many in the United States and Britain.
The destruction of Pan Am Flight 103 over Lockerbie, Scotland, in 1988 was the world's deadliest act of air terrorism until the September 11, 2001, attacks on New York and Washington, according to the FBI.
Al Megrahi was the only person convicted in the case.
As rebels swept into Tripoli two years after al Megrahi's release, politicians on both sides of the Atlantic called for him to be extradited, with the Americans demanding a trial in the United States, and British lawmakers saying he should return to prison in Scotland.
CNN's Nic Robertson tracked al Megrahi down at the palatial villa Moammar Gadhafi had built for him, apparently in a coma and near death. Al Megrahi's family said his son and mother were trying to care for him with oxygen and an intravenous drip, but with no medical advice.
Al Megrahi's death may make it impossible ever to get the full story behind the Lockerbie bombing.