Hassan Mohammed Zawahiru is terrorist working for Al-Qaeda.
During his life, Hassan Zawahiri was captured by the Russians and experimented upon in the Rajik gulag. One of these experiments Russia's Cobra tests, and Zawahiri was identified as having extraodrinary reflexes.
He later survived a missile strike caused by the Americans following the African embassy bombings, and also avoided over a dozen assassination attempts on his life by the Mossad. Zawahiri believed that his surviving all this meant that he had been chosen by Allah as a divine messenger.
Eventually Zahariri joined Al-Qaeda, moving through the ranks to be second-in-command to Osama bin Laden.
When the Americans launched their own reflexes study, Zawahiri's status from the Cobra tests were brought to light, and thus he was noted to be one of the few people who could disarm the CincLock-VII security system.
When Majestic-12 planned to initiate a Cold War by launching American Chameleon missiles at various places around the world, and started a bounty hunt to remove all those who would stop them, Zawahiru was put on their liquidation list.
Around this time, Allied forces received intelligence regarding Zawahiri's location, the Karpalov coalmine formerly run by the Soviets on the Afghanistan-Tajikistan border.
After Allied forces led by William Ashcroft infiltrated the mine, Zawahiri and his men began fighting back, using the mine's maze-like tunnels and several booby traps. Shortly after Elizabeth Gant and her Marines entered the mine, two additional forces suddenly appeared, interrupting the confrontation.
One of the unknown forces confronted Zawahiri, who defiantly claimed that they could not kill him, but was quickly proven wrong when Cowboy shot him in the chest point blank before cutting off Zawahiri's head.
Cowboy followed Demon's instructions to take Zawahiri's head (and a few others) to the French castle to claim the bounties. However when the Black Knight and Shane Schofield rescued Gant, they took with them the heads in order to use them to get access to the castle, claiming the bounties for them in the process.