General Ali Mohsen
Yemen's most feared military strongman, General Mohsen (left) was born in 1945 in Beit Al Ahmar village, Sanhan district. A career soldier, General Mohsen saved Mr Saleh from a coup attempt in 1979 and was his closest confidante for three decades. Relations soured when Mr Saleh began installing his sons and nephews in senior military posts. Gen Mohsen, reportedly a devout Shiite Muslim with good relations with Islamist groups, is known for a silent, ruthless manner.
Estimated fighting force: 50,000 plus tanks, artillery and other armoured vehicles
President Ali Abdullah Saleh
Born in 1942 in the same small village as General Mohsen, to a poor family, Mr Saleh (centre) grew up without a father. He reportedly had only a few years of formal education, instead joining the military in his teens and advancing rapidly. Mr Saleh, a Shiite Muslim of the Zaidi sect, confounded his critics and rose to the presidency by cleverly playing enemies against each other. His reputation is of a devious and unpredictable ruler famous for his brinkmanship. Described as cheerful, Mr Saleh has six sons and 10 daughters.
Estimated fighting force: 65,000 to 70,000 (including 35,000 Republican Guards) plus air force, artillery and navy.
Sheikh Sadeq al Ahmar
Recently described as "a mix of warlord, tycoon and kingmaker", the 55-year-old Sheikh al Ahmar (right) inherited the leadership of the Hashed tribal in 2007 after the death of his deeply revered father. One of ten brothers, most of whom are in powerful positions in business and politics, he is thought to be more open-minded and open to reform than many tribal leaders. Even before the uprising, Shiekh al Ahmar was openly critical of Mr Saleh and eventually sent fighters to protect protesters from government violence. He has no children but is known to support orphans.
Estimated fighting force: more than 40,000 plus RPGs and field artillery.