Great deluge had wiped off a failed version of humans. When the flood withdrew, it left rotting slime over the earth. From this slime and Gaia, Python was born. It was a gigantic serpent, sometimes referred as having draconic or even human-like features.
There are two versions of why Python died from a volley of arrows by Apollo. In one version the serpent was guardian beast of the oracle of Delphoi, which Apollo slew to claim oracle as his own.
In another version, the goddess Hera was jealous of Zeus and titaness Leto sharing a bed. She commands Python to attack Leto during her pregnancy in order to kill the titan as well as the unborn children. Leto manages to evade Python long enough to give birth to twin gods Apollo and Artemis. When Apollo reached adulthood, he slays the serpent dragon after giving it a chase all the way from island of Delos (which also bore the name of Leto's sister, Asteria) to Delphoi.