7. ?
8. King of Corona
9. Sultan of Agrabah
10. King of Arendelle

His rule was biased and unfairly and unreasonably strict, to the point that his own people found secret societies under his nose and drove his daughter to reckless choice eventually. He was impatient and got angry way too often, than required.

^What Anukriti said. Triton's rule is ironclad. He does not allow any opposition, and his lack of compromise defines him.

I don't think Triton is really bad ruler for his kingdom. I guess he is just too strict. And I can't stand with this King anyway.

If we're going to criticize a king for being too impatient and angry, I think we should eliminate this one first. He literally chases his advisor around with a sword because of some bad news. It's like Vader choking his officers when they fail him. Not really the best ruler.

^ at least he is chasing his advisor for bad news and not for stopping growth/progress on his biased opinions. Triton is taking wrong advise from his advisor and executing it.

^ Triton has a pretty open system though. Ariel can go anywhere in the ocean she wants, event to shark infested waters. Her one boundary is the surface because humans are such a foreign entity. And how do we not know that Triton is having his best academics study the humans. Just because he doesn't allow his 16 year old daughter to see them doesn't mean he's preventing growth. If aliens landed on earth they might end up being great people. That doesn't mean I'm gonna let a child interact with them though.

^ i was basing my argument inclusive of all sequels and prequels, which shows Triton to close off to a world who caused him personal harm and his attitude was same towards music, which was there in his kingdom but got banned because his personal mishap. A ruler should be ablw to look beyond personal feelings before putting rules in the kingdom. Whereas King from cinderella is shown to be more open minded and generous and understanding in sequels.
I'd have agreed to your point if coming solely from original movies only.