Jecht is Tidus' father, and a blitzball celebrity in his hometown of Zanarkand: he is perhaps best known there for the "Sublimely Magnificent Jecht Shot Mark III", a blitzball technique of his own creation; Tidus explains to Yuna that the name of the technique was a hoax designed for fans to keep coming back in the hopes of seeing the non-existent "Mark I" and "Mark II", which was successful. Jecht is a tall, muscular, and surly man armed with a large sword, though he never used it while as human in the game. He is voice acted by Gregg Berger in English and Masuo Amada in Japanese. It is mentioned multiple times in game that Tidus hates Jecht, because he believed that his mother always ignored him when Jecht was around, was under a lot of pressure due to his father's fame, and Jecht regularly insulted him and called him a crybaby; however, Jecht deeply loved and cared for Tidus, but found himself unable to express it in a kind way. Wanting Tidus to grow up to be strong, Jecht criticized him in the hopes that the insults would do the job, though Tidus took them at face value. Jecht is from a magically summoned replica of Zanarkand (Dream Zanarkand), created one thousand years before the events of Final Fantasy X; when a war was waging between Zanarkand and Bevelle. It was created by the leader of Zanarkand, summoner Yevon, who used the memories of those living in Zanarkand – fayth. As a consequence, Jecht and his son Tidus are dreams of the fayth. Yevon also created a malevolent creature called "Sin" to protect him, the fayth and Dream Zanarkand.
Before Final Fantasy X, Jecht was taken to Spira by Sin. Upon his arrival, Jecht constantly ranted about being from Zanarkand and was thrown in prison for insanity. However, he was soon bailed out by Braska and Auron, the former of whom asked Jecht to become his guardian on his journey to defeat Sin, stating that it would be "delightful irony" if the three of them managed to defeat Sin due to the church's low opinions of the three, "Braska marrying an Al Bhed, Auron having a relationship with a monk's daughter, and Jecht a drunkard". Beforehand, he met Yuna and told her numerous stories about his Zanarkand; because of this, Yuna is the only person who initially believes that Tidus is from Zanarkand in the present day. Jecht's alcoholism led him into trouble, and he gave up drinking anything stronger than Shoopuf milk after he attacked a Shoopuf in a drunken stupor for fear that his family would be ashamed of him and out of guilt that Braska had to pay for the damage. When they arrived at Zanarkand, Jecht accepted that he would never be able to return home and gave up his life to become Braska's Final Aeon, which defeated Sin for 10 years; beforehand, he requests that Auron take care of Tidus, believing that Auron could find a way to Dream Zanarkand, and Auron agrees. As a consequence, he became the new Sin. Sometime later, Jecht asserts some control over Sin, makes his way to the Dream Zanarkand, and communicates with the now-undead Auron, telling him that he wants him to take Tidus to the Spiran mainland, so Tidus could learn some life lessons and hopefully find a way to permanently dispose of Sin, and transports both Tidus and Auron to Spira. In Final Fantasy X, the protagonists gradually learn of Jecht's aforementioned actions, and also discover that Jecht is able to operate with free will when he hears the Hymn of the Fayth. Near the end of the game, they utilize this weakness to immobilize Sin. The group confront Jecht inside Sin and defeat him, Tidus finally making peace with his father. Yu Yevon is subsequently destroyed, sending Jecht and Tidus to the Farplane; Tidus slaps his father a jovial high-five, showing he has finally forgiven him.
Jecht has a small voice cameo in the final battles of Final Fantasy X-2 along with Braska and Auron, during which time they give Yuna encouraging words and advice on where to strike at the Machina Vegnagun. He also appears in a short flashback from the scholar Maechen.
Jecht is the (unwilling) villain representing Final Fantasy X in Dissidia: Final Fantasy where he is again voiced by Masuo Amada in the Japanese version and Gregg Berger in English. It is implied in game that he was once a hero, but became a villain, and Tidus' mission was to bring him back to the side of the heroes.