Heracles
Heracles was born after Zeus slept with Amphitryon's wife, Alkmene, and was raised by Amphitryon. As the son of Zeus and a mortal, Heracles possesses god-like strength and physical prowess.
Heracles does not make an appearance until midway through the play, when he returns home from Hades to find his family (his father Amphitryon, his wife Megara, and his three sons) moments away from execution at the hands of Lykos. Heracles decides to kill Lykos to defend his family using his favored weaponry—bow and arrows.
Shortly after, Madness infects Heracles on Hera's behalf for revenge, and he is driven to murder his family, leaving only Amphitryon as the sole survivor. Once Heracles comes back to himself, he is horrified by what he has done and decides to kill himself for his actions. He is persuaded from killing himself by Theseus, the king of Athens, who Heracles had rescued from Hades when he himself escaped. We last see Heracles leaning on Theseus as they head to Athens, where he will live out the rest of his life a broken man as the result of his actions.
Amphitryon
Amphitryon is the mortal father of Heracles and final survivor of Heracles' family after Hera takes her revenge. At the time of the play, he is an old man, something that he emphasizes and points out repeatedly throughout the duration of the play. His age makes him feel helpless to defend his family against Lykos, something that he laments along with the chorus of old men. In the end, he is spared from death when Athena appears and renders Heracles unconscious before he could kill Amphitryon.
Megara
Megara is Heracles' wife and the mother of three sons. She recognizes that Heracles cannot return from Hades to save them, and that fate cannot be changed. Despite this, Megara wishes for herself and her sons to face death at Lykos' hands with as much dignity as possible. While accepting that they must die, she asks Lykos that she may dress her sons in funeral clothing. She is saved by Heracles only to die moments later at his hands alongside her sons.
Lykos
Lykos is the usurper of Thebes that desires to kill Heracles' family. He is described as a cruel and evil ruler, and his actions support these descriptions throughout the play. He is killed off stage by Heracles with an arrow.
Three Sons of Herucles
Heracles' three sons have no lines throughout the play, though they are nearly always present alongside their mother. Each is killed by Heracles either by being shot with an arrow or by being beaten with a club.
Chorus of Old Men
The chorus in this play is a group of Theban elders. Their role is to reflect upon what has happened in the past as well as what is currently transpiring on stage. They provide emotional and historical explanations to the audience. They are unaffected by Lykos' desire to kill and Heracles' madness, only witnessing the aftermath of the bloodshed.
Iris
Iris is the messenger of the gods and accompanies Madness to Heracles' home. She describes how Hera was not allowed to get revenge on Heracles until after he had completed his tasks assigned by Zeus, but now that he is done, he will pay.
Madness
Madness is sent by Hera to attack Heracles and drive him to murder his family. Madness appears with Iris on Heracles' home's roof while he is defending his family against Lykos, and then descends into the home to inflict insanity upon him.
Theseus
Theseus is the ruler of Athens and friend of Heracles after Heracles frees him from Hades. After Heracles murders his family, Theseus offers him refuge in Athens, claiming that "Just in trouble, we come to know who is friend and who is not."
