In the Greek mythology the name Dionysos stands for two legendary figures, of which the second one, the God of wine, is the one far better known. The ancient Romans called the same God "Bacchus". (q.v. Triumph)
The orphic theology created the myth of Dionysos Zagreus.
It says that he was Zeus' and Semele's son. Zeus loved his son, a fact that evoked Hera's jealousy. She persuaded the Titans o kill Dionysos. He tried to escape Hera' fury by transforming into several different figures, but in the end the Titans tracked him down, and tore his body into pieces and gulped him. Zeus punished their deeds by throwing his thunderbolt at them and killing them. The story goes that humankind arose frome their ashes along with the Good and the Evil, united, according to their Genesis.
The second Dionysos
A second Dionysos is known to the Greek mythology, as the son of Zeus and his lover Semele. He correlates with the Roman God Bacchus and is considered as the God of wine and fertility.
Hera was so jealous that she persuaded Semele to ask Zeus to appear in the shape he would appear in front of Hera. So Zeus showed himself as a flash of lightning, killing Semele by burning her to death. As she had been pregnant with Dionysos, it is said, that Zeus took the child with him. Later a grapevine grew from the earth, on the lieu where she had died.
Zeus sewed the unripe fruit of womb in his own thigh. After Zeus had given birth to Dionysos, the boy was raisd by three foster mothers, in care of the nymphs of Nysa and later Silenus.
On the crossing from Ikaria to Naxos, tyrrhenic pirats captivated Dionysos, and wanted to sell him as a slave in Italy. But his bonds fell off by themselves and the ship was made to stop by ivy and wine tendrillars, which were winding up the mast and the sails. The terrified pirates jumped into the ocean and were transformed into dolphins. When Dionysos arrived in Naxos, he was welcomed and escorted by a cortage of nymphs, satyresses, Bacchae (Maenads and Thyiads), all adorned with ivy crowns, deer furs and thyrsoi. To honor the God they celebrated wild orgies. While engaged in the orgiastic delirium they tore young reindeers into pieces and ate the raw meat. Dionysos himself appeared in the shape of an animal, mostly as a ram or a taurus. By using his divine power he let wine, milk and honey swell from the earth. As the "liberator" (Lysios, Lyaios) he unleashed the people, deliberated them from their sorrows and let walls collapse.
Men who put up a fight against the dionysic fiests, were destroyed by Dionysos. To honor him, the Dionysia was celebrated in Greece and the Bacchanalia was celebrated in Italy.
There exist numerous illustrations of Dionysos and his cortage, e.g. on the Roman Campania reliefs.
Dionysos is also the God of the masks. His mask is attached to a stick, his cortage is wearing masks and masks were sacrificed. Due to this fact and the fact hat during the Dionysia numorous Tetralogies were shown (three Tragedies and one Satyrplay), he is also the God of tragedy.