As of 2016, who is the world's oldest head of state of a country?

Robert Mugabe of Zimbabwe turned 92 in February 2016 and still holds on to the reigns of power in his country. He has been a supreme leader for 36 years in spite of the country operating a democratic process of governance. There are so far no signs that should he survive long enough, he would fail to clinch yet again, his party's presidential nomination ahead of the 2018 presidential elections.

Queen Elizabeth II is 90 and has ruled United Kingdom since 1952. Being British monarch is a job for life. Plenty have put money on Her Majesty voluntarily stepping down but it’s a bet that never pays out, no matter how many generations of Windsors are awaiting their turn.

Essebsi is 89 and he has spent half a century in and around the corridors of power in Tunis.

The 88 year-old Halim of Kedah Malaysia also has the longest name of any head of state, going by the formal moniker Almu’tasimu Billahi Muhibbuddin Tuanku Alhaj sir Abdul Halim Mu’adzam Shah Ibni Almarhum Sultan Badlishah.