Zod is a minor antagonist in Superman, and the main antagonist in Superman II. He is one of Superman's arch-enemies and was made famous in the live-action movie Superman II where his speech alone entered icon status. He is a power-hungry Kryptonian criminal who has powers comparable to Superman himself but uses them in a malicious manner.
At the beginning of the movie Superman, Zod and his associates, Ursa and Non, were imprisoned in the Phantom Zone for their crimes of treason and sent into space - which, ironically, made them the only Kryptonians besides Superman to survive the planet's destruction. In Superman II, the explosion of a hydrogen bomb launched into space by Superman hits the Phantom Zone by chance, destroying it and releasing Zod, Ursa, and Non, who went to Earth. They discovered that they had the exact same powers as Superman, and naturally used them for evil, terrorizing the cities and even killing a few innocents.
Zod took over the president's office, but the president told him that Superman would never kneel before him. Lex Luthor joined forces with them, offering to tell them the location of the Fortress of Solitude, but eventually they decided to kill him. Superman came to stop them from terrorizing the city. Their attacks were able to affect each other, but in the end, Superman was outnumbered and lost, with Zod threatening to kill innocent people, and Superman flew back to the fortress. Luthor led Zod and his gang to the fortress.
Superman tricked Zod and his gang with multiple holograms, but when he had him in a headlock, Ursa threatened to tear Lois limb from limb unless Superman released him. Luthor seemingly joined forces with Superman, who then told him to get Zod and his gang into the molecular chamber that would take away the powers of any Kryptonian. Luthor then told Zod about this, and Zod, threatening to kill innocent people otherwise, forced Superman to enter, with Luthor activating the device.
However, Superman, knowing Luthor was going to double cross him, switched the device so that its rays would affect those outside it and not inside; therefore Superman was safe while Zod, Ursa, and Non were stripped of all power. Thinking he has won, Zod made Superman kneel before him and told him to take his hand and swear eternal loyalty. Superman crushed Zod's hand, picked him up, and threw him into a wall, where he fell into the icy abyss of the Fortress of Solitude. It's not known what happened with he after this, but he most probably died with Ursa and Non and didn't survive the fall.
Zod was critically acclaimed by both Superman fans and film critics, who agree that Superman II was an improvement over the predecessor.
In a cut of the film edited for television Zod, Ursa, and Nom survived and were taken into custody by law enforcement along with Lex Luthor.
In the Richard Donner cut of Superman II Superman turns back time, undoing the damage that Zod and his compatriots did to Earth, along with sealing the three Kryptonian criminals back into the Phantom Zone.