Agamemnon
King of Argos, Agamemnon does not appear until the middle of the play. He has been away at war for ten years, and upon returning he is portrayed definitively as a weary warrior. There is something fatal, resigned, in his every word. His language is particularly blunt. In the context of the play, Agamemnon might perhaps be considered over-masculine. There are several moments when his deeds, especially the sacrifice of his daughter, are considered too "daring" by other characters. Daring is used synonymously or euphemistically in the play to mean ambitious. It is through his indiscretion (Iphigeneia) that the curse of his house continues. And Agamemnon himself is claimed as its next victim.
Clytaemestra
Clytaemestra, queen of Argos, is a dangerous woman. But beneath her venom is a deep, inconsolable pain. We discover that, ten years prior to the action of the play, Iphigeneia, her only daughter, was sacrificed by Agamemnon in order to ensure fair winds for the sail to Troy. This event, more than anything, helps unlock Clytaemestra's character. For only someone as badly wounded as she could kill with so little remorse. When we meet her, she is, to all appearances, a stable, faithful, admirable woman. In her husband's absence, she has ruled Argos well. Yet there is some unwholesomeness about her, some suspicion or disturbance. She speaks of mothers and children, of sacrifice, once too often, perhaps. Even the Chorus is a bit wary of her. Clytaemestra is exceedingly shrewd; she is a temptress. During her ten year wait, she has constructed a terrible "snare" for her husband. In that time, her heart has spoiled and died within her. Eagerly, she offers herself to Zeus' as the instrument of Agamemnon's inevitable downfall. She strikes him three times and lustily retells how the blood spattered on her clothes. But she denies responsibility for the murder on grounds that she truly was fate's instrument. Her guilt is announced, however, with the appearance of Aegisthus, her lover.
Watchman
A man thoroughly weary of awaiting the bonfire that will signal the fall of Troy, the Watchman entreats the gods for respite. His soliloquy opens the play. On the roof of the palace, staring up at the stars which he has watched changed from day to day and season to season, the Watchman longs for the end of the Trojan war and the return of his king. He spies the fire and rushes to bring word to the queen. Introduced in his speech and character are several major symbols: seasonal cycles, transience, vigilance, weariness, Clytaemestra's manliness, the fire as sunrise, a disturbance in the royal house.
Herald
The Herald was presumably a youth when he sailed for Troy; now he is a man. He is inordinately grateful to be able to die on his home soil, something of which he had almost lost hope. He brings word of Menelaus, lost at sea. His meeting with the Chorus is a kind of father-son reunion. The Herald probably represents the return of Argive youth. He can be usefully contrasted with Iphigeneia, symbol of premature death.
Cassandra
The daughter of Priam and slave of Agamemnon, Cassandra is the famous unheeded prophetess. She has captured her at Troy by Agamemnon and carried her away (possibly as a concubine). Other characters perceive Cassandra as barbaric, animal, or incomprehensiblethis should be taken as a faithful sign of vision. She wildly forecasts not only Agamemnon's death, but her own. More distantly, Cassandra sees Clytaemestra's demise and the eventual resolution of the Oresteia as whole. She can also see backward: Cassandra provides the most explicit history on Atreus' house of any character in the play. The trespass she perpetrated against her husband with Apollo earned her the gift of incomprehensible prophecy. Her character can be usefully compared with Clytaemestra, who appears, to Cassandra alone, transparent and depraved from the very beginning.
Aegisthus
Aegisthus, son of Thyestes, cousin of Agamemnon enters at the end of the play, after Agamemnon's death. He is to be his tyrannical successor. Aegisthus takes credit for weaving the murder plot. He gives as his motivation revenge, but it is also power and ambition. During Agamemnon's absence, he has been Clytaemestra's lover. His overbold threats to the Chorus illustrate that he will be unfit, even disastrous, as a ruler.
Chorus of Argive Elders
Usually speaking in a group, the central importance of the Chorus cannot be overlooked. They represent the voice of Greek culture and tradition; they are the fathers whose sons have gone to war with Agamemnon and died at Troy; they are the citizens. The Chorus have seen too much sorrow, too much bloodshed but they also possess a broad enough perspective to know it cannot go on so horribly forever. Sad yet hopeful, the Chorus loyally await Agamemnon's return. Their knowledge of his house's history and of certain prophecies spoken after the sacrifice of Iphigeneia troubles their "conscience." They want to but cannot truly believe the king's homecoming will put an end to all Argos' woes. Moral barometers of the play, the Chorus are wise from long experience; they constantly offers opinions on wickedness, punishment, and righteousness. They are interpreters of the actionintermediaries for the audience.