In Final Fantasy X, Tidus's father is Jecht.
Jecht is a famous blitzball player from Dream Zanarkand and one of the central figures in Final Fantasy X. He is Tidus's father, although their relationship is strained by Jecht's harsh behavior and Tidus's resentment. When Sin attacks Zanarkand, Jecht is transported to Spira, where he becomes a guardian to the summoner Braska alongside Auron.
Jecht's role is much larger than that of a background parent. During Braska's pilgrimage, he sacrifices himself to become Braska's Final Aeon, defeating Sin temporarily. The cycle then transforms Jecht into the new Sin, the giant creature that has terrorized Spira for generations. Jecht later exerts limited control over Sin and helps create the circumstances that bring Tidus to Spira.
The main story eventually reveals that Tidus and his companions must confront Jecht inside Sin. This gives the game its emotional father-and-son climax: Tidus must defeat Jecht to end Sin's cycle, while also recognizing that Jecht sought redemption. Braska is Yuna's father, not Tidus's; Auron is Jecht's former companion, not his son.