Prince Hamidreza in prison

Saudi Arabia is an absolute monarchy, which makes Abdullah bin Abdul Aziz the king and prime minister. His deputies, Salman and Muqrin, are also from the ruling House of Saud, and the king-appointed cabinet includes more members of the royal family. While the monarchy is hereditary now, future Saudi kings will be chosen by a committee of Saudi princes, per a 2006 decree. Sabah Ahmed al-Sabah, age 84, has ruled Kuwait since 2006, when the previous emir died, setting off a minor succession crisis because the next-in-line was physically unable to recite the oath of office, possibly because of age-related health issues. Sabah took over instead; he rules the oil-rich nation as emir and head of the royal family, which has been in some form of power since the early 1700s.

Hamid Reza Pahlavi (left), brother of the deposed Shah of Iran sits in his cell in Evin Prison, Tehran, 10th February 1986. He was arrested after the revolution and jailed in Evin. (Photo by Kaveh Kazemi/Getty Images)