King Bhumibol Adulyadej of Thailand: 64 years
Queen Elizabeth II of the United Kingdom: 59 years
Sultan Abdul Halim of Kedah (Malaysia): 52 years
Hassanal Bolkiah of Brunei: 43 years
Qaboos Bin Said of Oman: 40 years
Muammar Gaddafi of Libya: 40 years
Queen Margrethe II of Denmark: 39 years
King Carl XVI Gustaf 0f Sweden: 37 years
King Juan Carlos I of Spain: 35 years
President Ali Abdullah Saleh of Yemen: 31 years
José Eduardo dos Santos of Angola: 31 years
Robert Mugabe of Zimbabwe: 30 years
Prince Khalifa bin Salman Al Khalifa of Bahrain: 30 years
Post Title → Current Longest Serving World Leaders Then and Now