Mutassim Billah Gaddafi (, also transliterated as Al-Moa'tassem Bellah Al-Qaddafi or Al-Mutasim Billah al-Qadhafi; 18 December 1974 – 20 October 2011) was a Libyan Army officer, and the National Security Advisor of Libya from 2008 until 2011. He was the fourth son of former Libyan leader Muammar Gaddafi, and a member of his father's inner circle. His mother was Safia Farkash, who had some Bosnian ancestry. He was captured during the Battle of Sirte by anti-Gaddafi forces, and killed along with his father.