Marduk & Nabû, Gods of Babylon
As Babylon conquered, so did its god — Marduk made king of heaven, with Nabû his scribe holding the stylus of fate.
Also: Marduk · Bel · Nabu · Nabû · Nebo · Babylon · Borsippa · fifty names
As Babylon rose to dominate Mesopotamia, its city-god Marduk rose with it — promoted in myth and cult to king of the gods, the victor over chaos in Enuma Elish, master of the fifty names that gather all divine powers to himself. His son Nabu, god of Borsippa, became the patron of the scribal art, of writing, wisdom, and the recording of destinies. Together father and son anchored Babylonian religion in the first millennium: Marduk the sovereign, Nabu the keeper of the stylus, whose annual procession to Babylon was a high point of the religious year.
In short
Marduk, city-god of Babylon exalted to king of the gods in the second–first millennia, and his son Nabû of Borsippa, god of the scribal art and patron of wisdom and writing.
Where it’s found
Enūma Eliš (Marduk's exaltation and fifty names; akkadian-pending); 'A hymn to Marduk for a king' (ETCSL 2.8.5.b, in corpus) attests early Marduk praise
How the idea developed across Sumer, Babylon & Assyria
Marduk's exaltation is the theological reflex of Babylon's political rise (Old Babylonian onward, climaxing in Enuma Elish). Nabû grows in importance through the first millennium, eventually rivaling his father in popularity. In Assyria the supreme role is held instead by Aššur. (Nabû is this project's patron of my own scribal craft.)