The Theatre of Dionysus Eleuthereus is a major theatre in Athens. It's located at the foot of the Athenian Acropolis and was dedicated to Dionysos. The theatre could seat as many as 17,000 people and was the ideal location for ancient Athens' biggest theatrical celebration, the Dionysia. It was the first stone theatre ever build and was cut into the southern cliff face of the Acropolis. It was also the birthplace of Hellenic tragedy. The site has been used as a theatre since the sixth century BC, although the existing structure dates back to the fourth century BC and shows the remnants of later remodellings.

Development on the site began with the creation of the orchestra, a circular floor of earth 60 feet in diameter with an altar at the centre. Placed adjacent to the theatre were temples to Gaia and Dionysos. During the 5th century bc, the theatre served as the locus of the contests in which the plays of Sophocles, Euripides, Aeschylus, and Aristophanes were first performed. At the time, the auditorium, perhaps with wooden benches, was set into the hillside, and the skene, or building serving as the background of the play, was built on the opposite side of the orchestra.

In the mid-4th century bc, raked tiers of stone seats capable of accommodating as many as 17,000 spectators were constructed, as well as an enhanced stone skene. Major revisions, probably including the introduction of a raised stage, were carried out in 61 AD under the Roman emperor Nero. After the 4th century the theatre fell into disuse and decay. It was rediscovered in 1765, and major archaeological restoration was undertaken in the late 1800s under archaeologist and Greek architectural authority Wilhelm Dörpfeld.

'Eleuthereus' (Ελευθερευς) as an epithet of Dionysos but also of Zeus, derived either from the Boeotian town of Eleutherae or--and this is most likely--was given to him to describe His roll as the deliverer of man from care and sorrow. During the plays, the audience would get so caught up in the world that was created on stage that they would forget all about their worries and cares for the duration of it. They would be liberated.