I’ve read that Fidel Castro, who’s been in office since 1959, is the longest ruling current head of state. Who’s the second longest current head of state? Is it perhaps Qaddafi, who I believe has ruled Libya since 1969?
Hmm. I think the premise is flawed. Elizabeth II has been a head of state since 1952.
Maybe Castro is the longest-serving head of government?
Ah ha! Even better, King Bhumibol Adulyadej of Thailand has been king since 1946!
President Omar Bongo of Gabon has been in office since December 1967.
Here’s a list of the longest-ruling heads of state or government.
The top 10:
1 Bhumibol Adulyadej King Thailand 9 Jun 1946
2 Elizabeth II Queen United Kingdom 6 Feb 1952
3 Fidel Castro Ruz Prime Minister Cuba 16 Feb 1959 (1)
4 Malietoa Tanumafili II Sovereign Chief Samoa 1 Jan 1962 (2)
5 Taufa'ahau Tupou IV King Tonga 15 Dec 1965 (3)
6 Muda Hassanal Bolkiah Sultan Brunei 5 Oct 1967 (4)
7 Omar Bongo President Gabon 2 Dec 1967
8 Col. Muammar al-Gaddafi "Revolution Leader" Libya 1 Sep 1969 (5)
9 Khalifah ibn Salman Al Khalifah Prime Minister Bahrain 19 Jan 1970 (6)
10 Qaboos ibn Said Al Bu Sa`idi Sultan Oman 23 Jul 1970
It would appear from that list that Bongo is the second-longest serving non-hereditary ruler after Castro, and Gaddafi the third.
That is one unfortunate name…
I would argue that the King of Thailand is the second longest ruling head of state. The longest would have to be the Dali Lama, who has through reincarnation remained the head of state of Tibet since 1391. 
At least he’s not president of the Congo . . .
'least he’s not named Akbar.
I was thinking that since he hasn’t been defeated in any sort of election we haven’t had the opportunity to see the headline “BONGO BEATEN”
It could be worse: a former president of Zimbabwe, Canaan Banana, was imprisoned by the new president on trumped-up sexual charges… leading to the headline BANANA CONVICTED OF SODOMY.