In
Call of Duty 4: Modern Warfare, Four Horsemen is the nickname for a group of the most wanted bad guys, who were the main targets. Tbe first one iz Imran Zakhaev, the second one is Khaled Al-Asad, the third one is Zakhaev's son, Victor Zakhaev. The fourth horseman still remains unknown. Some believe that he was the executed president (His execution was watched from
first person view), Al-Fulani, because he betrayed them. In the briefings for some missions, a picture of three of them is shown with an "X" over their head, so you can figure out which ones you've eliminated. When you see that photo for
the first time, Fourth Horseman's head is already X-ed.