Nibiru, to the Babylonians, was the celestial body or region sometimes associated with the god Marduk.
While the relationship between Ea and Marduk is marked by harmony and an amicable abdication on the part of the father in favour of his son, Marduk's absorption of the power and prerogatives of Enlil of Nippur was at the expense of the latter's prestige. After the days of Hammurabi, the cult of Marduk eclipsed that of Enlil; although Nippur and the cult of Enlil enjoyed a period of renaissance during the four centuries of Kassite control in Babylonia (c. 1570 BC–1157 BC), the definite and permanent triumph of Marduk over Enlil became felt within the Babylonian empire. The only serious rival to Marduk after ca. 1000 BC was Aššur in Assyria. In the south, Marduk reigned supreme. He is normally referred to as Bel "Lord", also bel rabim "great lord", bêl bêlim "lord of lords", ab-kal ilâni bêl terêti "leader of the gods", aklu bêl terieti "the wise, lord of oracles", muballit mîte "reviver of the dead", etc.
When Babylon became the capital of Mesopotamia, the patron deity of Babylon was elevated to the level of supreme god. In order to explain how Marduk seized power, Enûma Elish was written, which tells the story of Marduk's birth, heroic deeds and becoming the ruler of the gods. This can be viewed as a form of Mesopotamian apologetics. Also included in this document are the fifty names of Marduk.
In Enûma Elish, a civil war between the gods was growing to a climactic battle. The Anunnaki gods gathered together to find one god who could defeat the gods rising against them. Marduk, a very young god, answered the call and was promised the position of head god.
When he killed his enemy, he "wrested from him the Tablets of Destiny, wrongfully his" and assumed his new position. Under his reign humans were created to bear the burdens of life so the gods could be at leisure.
Marduk was depicted as a human, often with his symbol the snake-dragon which he had taken over from the god Tishpak. Another symbol that stood for Marduk was the spade.
Babylonian texts talk of the creation of Eridu by the god Marduk as the first city, "the holy city, the dwelling of their [the other gods] delight".
Nabu, god of wisdom, is a son of Marduk.
Marduk was included in the film "Indiana Jones and The Infernal Machine". Dr.Jones had to fight him to release Sophia of his custody