Leader of the Abu Sayyaf terrorist group during both the April 2000 Sipadan and May 2001 Dos Palmas hostage incidents in the southern Philippines. Along with his brother Abdurajak Janjalani, he helped found the Abu Sayyaf movement during the breakup of the Moro National Liberation Front (MNLF) after the signing of the ARMM (Autonomous Region of Muslim Mindanao) agreement.

He has sworn to avenge his brother, who was killed in a 1998 encounter with police under the Ramos administration. Since then, his organization has been a constant thorn in the side of both the Estrada and Arroyo administrations. He has been charged with kidnapping, several acts of terrorism (including the bombings of several churches and mosques in Sulu and Jolo) and numerous other crimes.

Although in the beginning, under Abdurajak Janjalani's watch, the Abu Sayyaf claimed to be fighting to remove Christian influence from Muslim Mindanao, after his death, Khadafy Janjalani seems to have let the Abu Sayyaf degenerate into just another kidnap-for-ransom bandit gang (albeit a well-armed and well-funded gang). Unlike his brother, who was an Islamic scholar, his only known skills are with explosives.

Details from ANC Channel 21 broadcast, Philippine Daily Inquirer, and Asiaweek.