Dionysia
The Dionysia was a large festival in ancient Athens in honor of the god Dionysus, the central events of which were the theatrical performances of dramatic tragedies and, from 487 BC, comedies. It was the second-most important festival after the Panathenaia. The Dionysia actually consisted of two related festivals, the Rural Dionysia and the City Dionysia, which took place in different parts of the year. They were also an essential part of the Dionysian Mysteries.
Read more about Dionysia.