Hades

Hades is the main antagonist in Clash of the Titans and later reformed in Wrath of the Titans after Zeus apologized for abandoning Hades in the Underworld.

Clash of the Titans (2010 remake)
Hades first appears after sending the Furies on the people of Argos and attacks the ship Perseus and his family are on.

Appearing on Mount Olympus, Hades begins to manipulate events to enact his revenge on his younger brother Zeus for leaving him hated and alone in the Underworld. He uses Zeus' anger at his advantage and manages to get permission to go down to where the mortals are, going around celebrating about bringing about the downfall of the Olympians.

Hades appears back to Argos, where his surprised to find Perseus is still alive and sole survivor of the ship. He approaches Cassiopeia, calling her a foolish mortal Queen, esspecially since the Gods are above them. He reveals his identity to the mortals, who all gasp in shock. To punish the city for their queen's insolence, Hades ages Cassiopeia and threatens that he will unleash the Kraken in ten days when the sun is eclipsed and have the entire city wiped from the earth, unless they sacrifice Princess Andromeda, who they have so foolishly compared to the gods to. Before disappearing, Hades reveals it is the will of Zeus and reveals to Perseus that the Lord of Olympus is his father.

Hades makes a deal with Acrisius: he'll destroy Zeus in exchange for the mortal man to destroy Perseus. Hades unleashes the Kraken and reveals to his brother he is going to destroy Zeus for leaving him in the Underworld.

On the tenth day of the deadline, Hades unleashes the Kraken but makes his intentions to Zeus: he needs the fear of humans to fuel on power. However, his  plan falls through when  Perseus uses Medusa's head to turn the Kraken to stone. Hades confronted and taunted Perseus of how he would live forever as a god; but with the  combined  forces of father and son, Perseus and Zeus  banish Hades back into the Underworld with Perseus' sword and Zeus' lightning. They both predict that Hades will return and attempt to take advantage of men growing weak and their fears again

Wrath of the Titans
Hades returns in the 2012 sequel to the remake. He has aligned himself with Ares and Kronos by restoring his father back to power by draining Zeus of his essence. However after Zeus apologizes for abandoning Hades in the Underworld to be hated and feared. Hades forgives Zeus when his younger brother is nearing death and uses the last of his strength to revive his brother. The two join the human on the battle field to defend their allies from Kronos. Zeus is badly wounded and passes away from his wounds before making his peace with Perseus.

Hades tells Perseus that now he will travel the world as a mortal, thinking that now he has no powers, he will be better off without it.