The key creation myth in Greek mythology can be found in Hesiod's Theogony. It depicts a succession of power struggles between various divine forces as the universe gradually moves away from the chaos of primordial disorder towards the civilized order established and guaranteed by the Olympians and Zeus.

In Hesiod's telling, the oldest and most fundamental force in the universe is Chaos, which predates everything else. After Chaos emerges Gaea (the Earth itself), Tartarus, and Eros. Barry B. Powell discusses this earliest stage in the following terms:

Some think he meant the four to represent aspects of the primeval stuff from which the world emerged: a gaping (Chaos), the foundation of all that is (Gaea), the underside of that foundation (Tartarus), and the principle of sexual attraction, which ensues future generation and change (Eros). (Classical Myth (4th edition), Upper Saddle River: Pearson Prentice Hall: 2004, p. 77)

From this foundation, several generations succeed one another as the universe steadily moves away from this unformed primordial chaos (in which it originated) towards civilization and order. From the coupling of Gaea and her son, Uranus (the sky), emerge the titans. Cronus, with the support of his mother, castrates his father, separating sky from Earth, and emerges as the Earth's first ruler. Later, Cronus and the Titans will be overthrown by the Olympians in turn. Each of these various transitions, culminating in the triumph of the Olympians over the Titans is viewed as another step in this gradual path that brings greater order to the universe.

Of course, just as one of the central themes of Greek mythology is the establishment of order, that order also must be protected against the primordial forces of Chaos, as Zeus must outsmart or defeat various challenges to his rule (which tend to have the backing of Gaea, emerging as an opponent to the Olympians). Just as Zeus overthrew his predecessors, he too must remain active lest he himself be overthrown.

As far as the creation of humanity goes, Powell writes:

The Greek tradition shows curiously little interest in the ultimate origins of mortals. Hesiod offers no explanation at all, although he does discuss other matters pertaining to the early life of human beings, as we will see later in this chapter. Scattered references in later authors often are contradictory. Sometimes Zeus himself is identified as the creator of mortals, sometimes various gods working together. But most often the maker as said to be Prometheus" (109-110)

One thing worth noting about the Greek cosmology (and the creation of mankind) is that the creation of men and women are actually two separate events: men were created first and women later. In the Greek creation story, women were explicitly created as a punishment on humanity by Zeus. This is represented in the story of Pandora, the first woman, who, by opening Pandora's box, introduces all suffering into the world.