King Abdullah bin Abdulaziz

Position: King of Saudi Arabia
Biography: King Abdullah spent the last few weeks of 2010 in the US under going back surgery for a herniated disc and Saudi watchers will be following his progress closely in the months ahead.

His half-brother, Crown Prince Sultan bin Abdulaziz assumed charge in his absence. Since both men are in their mid-80s and Prince Sultan has himself suffered serious health problems in recent years, the incident has thrown the question of succession to the fore once more. The third in line, Interior Minister Prince Nayef bin Abdulaziz is in his mid-70s.

King Abdullah is one of more than 35 sons of Ibn Saud, the founder of modern Saudi Arabia. King Abdullah ascended to the thrown in 2005, but was de facto ruler for 10 years before this, after his half-brother King Fahd suffered a debilitating stroke.

In 2006, King Abdullah set up the Allegiance Council to determine the eligibility of future generations of kings and heirs to ascend to the throne.