The Python (Πύθων) of Delphi was a creature with the body of a snake.
The Python used to dwell on Mount Parnassus, in central Greece. Wherever the Python went, it diffused an obnoxious smell and spread mischief and death. Python was once sent out by Hera, the wife of Zeus, in order to chase the pregnant Leto, a lover of Zeus, so that she couldn't settle anywhere to give birth. Zeus felt sorrow for Leto and transformed her into a quail (ortyx) in order to give birth to their twin children, Apollo and Artemis.
By the time Apollo, the son of Leto, was only four days old, he was already a strong boy. A silver bow with golden arrows, given to him by the blacksmith Hephaestus, made the young god decide to kill Python and take revenge. Soon, Apollo went to the creature’s cave to seek after Python. When the creature faced Apollo, it started boiling with rage and lunged at Apollo to devour him. But Apollo was faster and managed to throw an arrow to Python, piercing him right on its forehead. Python cried of terror and his scream could be heard all over the canyons of Mount Parnassus. It struggled hard to survive... but in the end it surrendered to death.
The death of the Python filled Apollo with joy, so he happily took his lyre and started playing a song of victory, giving joy to people all around.
This was the moment when
Apollo became the god of the Music!
Right after he finished his song, Apollo took the creature and buried it under the slopes of Mount Parnassus. On its surface he built the oracle of Delphi, the most famous oracle of ancient Greece. However, Apollo had committed a crime and, according to the laws of Mount Olympus, he needed to be purified. Therefore, Zeus ordered from Apollo to institute the Pythian Games at Delphi so that athletic and musical competitions could be hosted. Apollo followed the order and he even took part in the games himself. From then on, the Pythian Games were held every four years in Apollo's honor.