Square's 2001 role-playing video game Final Fantasy X is the tenth game of the Final Fantasy series. It features several fictional characters designed by Tetsuya Nomura, who wanted the main characters' designs and names to be connected with their personalities and roles in the plot. The game takes place in Spira, which features multiple tribes. The game's sequel, Final Fantasy X-2, was released in 2003. It takes place two years after the events of Final Fantasy X and features both new and returning characters.

There are seven main playable characters in the game, most prominently protagonist Tidus, a skilled blitzball player from Zanarkand who becomes lost in the world of Spira after an encounter with an enormous creature called Sin and searches for a way home. He joins the summoner Yuna, who travels towards Zanarkand's ruins to defeat Sin alongside her guardians: Kimahri Ronso, a member of the Ronso tribe; Wakka, the captain of the blitzball team in Besaid; Lulu, a stoic black mage; Auron, a famous warrior and an old acquaintance of Tidus; and Rikku, Yuna's cousin who searches for a way to avoid Yuna's sacrifice in the fight against Sin. The leader of the Guado tribe, Seymour Guado, briefly joins the party for a fight, but is revealed to be an antagonist in his quest to replace Tidus' father, Jecht, to become the new Sin. Final Fantasy X-2 features Yuna, Rikku, and the newly introduced Paine as playable characters in their quest to find spheres across Spira and find clues regarding Tidus' current location. During their journey, they meet Paine's former comrades, who are related to the spirit of an avenger named Shuyin.

The creation of these characters brought the Square staff several challenges, as Final Fantasy X was the first game in the franchise to feature voice acting. They also had to feature multiple tribes from different parts from Spira with distinctive designs. Various types of merchandising based on the characters have been released. The characters from Final Fantasy X and its sequel were praised by video game publications, owing to their personalities and designs. The English voice acting initially received mixed response, but X-2's dub received a better response.

Tetsuya Nomura was the character designer for Final Fantasy X and X-2. Since art director Yusuke Naora convinced the Square staff to make Final Fantasy X an Asian-themed game, Nomura designed the characters to give them an Asian look. Nomura first illustrated the characters' faces and started adding details upon receiving information from the staff. Since the PlayStation 2's capabilities allowed for featuring more detail, Nomura did so with the characters and asked the staff to make them consistent. The hardest part of his work involved making the characters' clothes identical between full motion scenes and in-game.

Nomura has expressed that after designing serious and moody main characters for Final Fantasy VII and VIII, he wanted to give Tidus a cheerful attitude and appearance. This is reflected in the name Nojima chose for him, as Tiida is the Okinawan word for "sun". Nomura has also mentioned a contrast between the lead male and female protagonists was established by Yuna's name meaning "night" in Okinawan. Since Tidus did not originate from Spira, his outfit was made to stand out from those of the world's inhabitants. Nomura also placed image colors to each main character to give hints regarding their personalities. Since both the player and the main character find themselves in a new world, Nojima wanted Tidus' understanding of the world to reflect the player's progress, a connection that allowed the player to advance Tidus' first-person narration of most of Final Fantasy X.

Sub-character chief designer Fumi Nakashima's focus was to ensure that characters from different regions and cultures bore distinctive characteristics in their clothing styles, so that they could be quickly and easily identified as members of their respective sub-groups. For example, she has said that the masks and goggles of the Al Bhed give them a "strange and eccentric" appearance, while the Ronso's attire lend to them being able to easily engage in battle.

Final Fantasy X features innovations in the rendering of characters' facial expressions, achieved through motion capture and skeletal animation technology. This technology allowed animators to create realistic lip movements, which were then programmed to match the speech of the game's voice actors. Nojima has revealed that the inclusion of voice acting enabled him to express emotion more powerfully than before, and he was therefore able to keep the storyline simple. He also said that the presence of voice actors led him to make various changes to the script, in order to match the voice actors' personalities with the characters they were portraying. Despite being worried about the inclusion of voice acting, Nomura was satisfied when hearing their clips, as he said that the characters became full of life. The voice acting brought difficulties in the making of the English version of the game, as the localization team had to translate Japanese dialogue into English-oriented lines that would fit the characters' lip movements.

Before starting development of Final Fantasy X-2, Square had planned to make a game following the story of Jecht, Auron and Braska ten years before the events of FFX, but they felt that they would end with a "traditional game". For X-2, while Nomura still remained as character designer, Tetsu Tsukamoto designed the new costumes of the main characters to distance the game from its predecessor. The outfits are meant to represent the changes in the world of Spira after two years of peace. The use of three female characters was inspired by multiple films that depict strong female leads. To reinforce this concept, the staff made sure to make the protagonists still look feminine while changing into multiple type of warriors such as the Samurai form, in which the characters wield large swords.