Mustafa Setmariam Nasar, also known as Abu Musab al-Suri, is an al-Qa'ida member and former trainer at the Derunta and al-Ghuraba terrorist camps in Afghanistan.

Born in Aleppo, Syria in 1958, Nasar was a member of the radical Syrian Muslim Brotherhood. He fled Syria in the 1980s and traveled widely throughout the Middle East and North Africa, before associating with the Algerian Islamic Group. He settled in Madrid in 1987 and gained Spanish citizenship through marriage.

While in Spain, he authored a series of inflammatory essays under the pen name Umar Abd al-Hakim. In 1995 he moved to United Kingdom and served as a European intermediary for al-Qa'ida. Nasar traveled extensively between Europe and Afghanistan throughout the late 1990s, finally moving his family to Afghanistan in 1998.

He attempted to organize his own extremist group prior to September 11, 2001 - but in the wake of the attacks he pledged loyalty to Usama Bin Ladin as a member of al-Qa'ida. While in Afghanistan, Nasar worked closely with Midhat Mursi al-Sayid 'Umar AKA Abu Khabab al-Masri to train extremists in poisons and chemicals. Nasar also conducted training at the al-Ghuraba camp in Afghanistan.

He is likely in Afghanistan or Pakistan. Recent unconfirmed press reports suggest that he may have had a role in the March 11, 2004 Madrid Bombings.