Who is the Tritagionist of this Series?

[Reverof Enola]

I mean is it King Mickey for making a major appearance in every game, Roxas for having some importance, but has his own game and for being a false protagionist once, or is it someone else entirely. Since Riku serves as the deuteragionist.

[Del Murder]

Whaa?

[Reverof Enola]

Whaa?
You know the third main character? Where you have the protagionist , deuteragionist, and tritagionist? Ex: DBZ has P, Goku , D: Gohan , and T: Vegeta

[Pheesh]

I would have thought Sora, Donald and Goofy are the three...

[Formalhaut]

I've learned new words! Hooray!

Um... I can't really say. Sora's obviously the protagonist. The deuteragonist could be either Kairi or Riku or Mickey. I'd lean towards Mickey myself because he's always been good, while Riku's more of an anti-hero. Finally, the tritagonist is probably Kairi.

Of course, Goofy and Donald are very important, but for the overarching story of the entire series, that's who'd I go for.

[Del Murder]

Jiminy Cricket.

[NeoCracker]

...Morgan Freeman?

[Pheesh]

Jiminy Cricket.

Was that an answer or an exclamation of surprise?

[Del Murder]

Both!

[Ouch!]

I'd lean towards Mickey myself because he's always been good, while Riku's more of an anti-hero. Finally, the tritagonist is probably Kairi.
First, in protagonist the meaning of the prefix "pro-" is primary. It implies nothing about the character's nature except that they are the most important character to the narrative. The protagonist of a story can be the villain in moral terms (an antihero). Similarly, antagonist only implies that the character(s) who fulfills such a role is in opposition to the protagonist.

Second, Riku is not an antihero. He is temporarily allied with an antagonist, but he is being manipulated. Riku's storyline follows the prototypical hero's journey more closely than Sora's as he experiences the essential phases of revelation and atonement in a way that Sora does not (finding out that he has been manipulated and then turning to help Sora). He is the best candidate for deuteragonist, if there is one.

As for the OP's question, the idea of a trinity of protagonist, deuteragonist, and tritagonist is irrelevant in the discussion of an ensemble cast. There is a reason that the terms deuteragonist and tritagonist are very uncommon outside of discussion of classical Greek theater (in which the roles were played by three actors who were assigned the roles of protagonist, deuteragonist, and tritagonist). Kingdom Hearts has a far too vast and varied cast of narratively crucial characters to try and shoehorn them into these three roles.

[Mercen-X]

Personally, I'd say the antagonist is Maleficent for being there most of the time to bug the heroes. Then I'd say Xehanort is the dueteragonist/secondary antagonist for being the next most important character to the series. That would leave Riku as the tritagonist being the third most important character to the series.

[Ouch!]

Wait, wait, wait.

Xenanort is the secondary antagonist in a series that the creator of which refers to as the Xehanort Saga?

[Formalhaut]

Maleficient is definitely a secondary antagonist. She's always pops up, but is merely a front, masking the true overarching antagonist. Once she is dealt with, normally the true enemy comes into view. Hell, in KHII she evens teams up with Sora to defeat Organisation XIII, granted only because they are the greater of two evils, but still.

[NeoCracker]

This is one of the silliest discussions on Kingdom Hearts I have ever seen.

[Formalhaut]

This is one of the silliest discussions on Kingdom Hearts I have ever seen.

I think we ran out of "serious discussions" long ago.

[I Don't Need A Name]

This is one of the silliest discussions on Kingdom Hearts I have ever seen.

I think we ran out of "serious discussions" long ago.

Kingdom Hearts has had 'serious discussions'? What is Kairi's Keyblade and OMGZ AXEL IS RENO are far from serious discussions..

[Mercen-X]

lol

[The Summoner of Leviathan]

Actually, I think the last serious discussion I recall was about cosmology.

[qwertysaur]

Lea

[Mercen-X]

Good one

[DMKA]

Clearly the tritagionist is DARKNESS.

[Sephiroth]

"Second, Riku is not an antihero. He is temporarily allied with an antagonist, but he is being manipulated."

At the beginning he can decide what he wants. And he wants to go that way. Only later it is really some kind of manipulation, when Ansem steps in. Maleficent already tries to manipulate him and partly succeeds but he could still say "no". He just does not want to. Even when Ansem steps in he could say no. But once they fused it is too late. AND even then he partly succeeds to stop Ansem. That is not pure manipulation.

If you consider Riku, Kairi and Mickey also being the 2. protagonist then it is Terra. His past, his story and his connection to Xehanort makes him pretty much one of the most important main characters of Kingdom Hearts.