Some state leaders in the world have held onto their positions for decades. States where head of state differs from head of government are mainly parliamentary systems. Often a leader holds both positions in presidential systems or dictatorships. Some states have semi-presidential systems where the head of government role is fulfilled by both the listed head of government and the head of state.
The list below is of current state leaders ordered by their continuous tenure in a position of national leadership. In countries with different heads of state and heads of government, both offices are listed. For leaders who held the same office prior to their state’s independence, the start of their tenure is used, not independence. Acting presidents are included in this list, but if a leader has non-consecutive terms, only the current period of service is listed.
Here are the top 20 longest serving state leaders in the world.
| Rank | Name | Country | Assumed office |
| 1. | Hassanal Bolkiah | Brunei | October 4, 1967 |
| 2. | Carl XVI Gustaf | Sweden | September 15, 1973 |
| 3. | Paul Biya | Cameroon | June 30, 1975 |
| 4. | Teodoro Obiang Nguema Mbasongo | Equatorial Guinea | August 3, 1979 |
| 5. | Ali Khamenei | Iran | October 13, 1981 |
| 6. | Hans-Adam II | Liechtenstein | August 26, 1984 |
| 7. | Hun Sen | Cambodia | December 26, 1984 |
| 8. | Yoweri Museveni | Uganda | January 29, 1986 |
| 9. | Mswati III | Eswatini | April 25, 1986 |
| 10. | Harald V | Norway | June 1, 1990 |
| 11. | Isaias Afwerki | Eritrea | April 27, 1991 |
| 12. | Emomali Rahmon | Tajikistan | November 19, 1992 |
| 13. | Alexander Lukashenko | Belarus | July 20, 1994 |
| 14. | Letsie III | Lesotho | February 7, 1996 |
| 15. | Denis Sassou Nguesso | Congo | October 25, 1997 |
| 16. | Henri | Luxembourg | March 3, 1998 |
| 17. | Abdullah II | Jordan | February 7, 1999 |
| 18. | Hamad bin Isa Al Khalifa | Bahrain | March 6, 1999 |
| 19. | Mohammed VI | Morocco | July 23, 1999 |
| 20. | Vladimir Putin | Russia | August 9, 1999 |
