Igigu, or Igigi, is an Akkadian collective name for a group of gods, and the text that fixed it in the modern imagination is Atrahasis, the Old Babylonian poem of the flood. The poem opens on a world with no people in it, where the gods do their own labour and find it crushing. Seven great Anunnaki, it says, were making the Igigu bear the work. The junior gods dug the watercourses and carried the earth, and in the end they refused to carry on. They burned their tools, went to the house of Enlil by night, and surrounded it.
The tablet breaks up at that point, but the outcome does not. The senior gods had to find another way for the work to be done, and the answer was humanity, made so that the labour the Igigi had thrown down would fall to people instead. That is the Mesopotamian account of why anyone is here at all, and it starts with a strike.
The Igigi turn up elsewhere, less dramatically. The prologue to the Code of Hammurabi says that the Anunnaki raised Marduk high among the Igigi, which is the one piece of evidence placing a named god securely inside the group. The Anzu myth speaks of an assembly of the Igigu, though whether that was a standing institution or a turn of phrase is doubted. They are named in Enuma Elish, in the poem of Erra, and in incantations and prayers down to the end of the cuneiform tradition. What they are never given is a face: because the word names a group and not a figure, no image of the Igigi is known.