The Iliad: Character Profiles

Zeus: Zeus is the ruler of the gods.  He has absolute control over the eventual destinies of humans, but other gods can influence Zeus in the short term, or even interfere with his intentions.  The will of Zeus always prevails, despite any efforts of the other gods to change it.  Zeus favors the Greeks in the battle of the Trojan War, but he makes short-term concessions to the gods that favor the Trojans by making the Greeks' victory occur only after years of fighting and tragic sorrow.
Hera: Hera is Zeus' jealous wife.  She is very angry because Zeus has pity on Troy.  Hera is the boldest of the gods who challenges Zeus.  She manipulates both other gods and mortals in order to try to keep Zeus from destroying Troy.  Hera realizes that her attempts are futile, but she tries to bypass Zeus' will that the Trojans have glory as well as the Greeks. 
Apollo: Apollo is the god of the sun, and favors the Trojans.  In the beginning of the Iliad, it is Apollo who brings a plague to the Greeks, because of Agamemnon's dishonor to one of his human priests.  This act becomes significant because it sparks Achilles to leave the fighting, and makes possible the rest of the book.
Aphrodite: Aphrodite is the goddess of love, and she is the patron goddess of Paris, the son of the Trojan king Priam.  Aphrodite is one of the more active gods in the Iliad, and she joins the battle on the side of the Trojans and actively fights with them.  Unlike Hera, Aphrodite tries to directly influence the outcome of the war by fighting in battle alongside the Trojans, and whisking Paris away from potentially lethal situations many times.  Aphrodite also protects Hector, Paris' brother, but has to abandon him during a key battle by edict of Zeus.
Athena: Athena is the goddess of wisdom, and she favors the Greeks.  Athena is the goddess who adheres to Zeus' will more strictly than the other gods.  She protects the Greeks, specifically Diomedes, Odysseus, and Achilles.  Athena is a calming and reasoning influence, and helps to avoid conflict when she calms Achilles after he has threatened Agamemnon because Agamemnon unfairly took Achilles war spoils.
Thetis: Thetis is the mother of Achilles.  She is a water nymph, and she does not want her son to fight, because of a prophecy that ensures Achilles' death if he continues to fight.  She is a minor god, and so she can only beg Zeus' for mercy on behalf of her son.
The Greeks: Also known as Acheans, Argives and Daanans. 
Achilles: Achilles is the Greek's most powerful warrior without question.  However, he believes that his superiority of fighting ability gives him the unquestionable right to lead the Greek fighters as a king.  When he disagrees with Agamemnon, the legitimate leader of the Greek fighters, Achilles sulks away from the battle, knowing that the Greeks will suffer without him.  The main focus of the Iliad is Achilles' internal struggle with leaving the fighting.  On one hand, Achilles has been wronged y Agamemnon; also, Achilles remembers the prophecy of his death and must remember that if he fights, he will surely die.  On the other hand, by not fighting, Achilles' friends in battle are suffering, and eventually, his best friend Patroclus is killed because of Achilles' refusal to fight. 
Agamemnon: Agamemnon is the leader of the Greek forces.  He is only a mediocre warrior but he is respected because he is older than Achilles and he has more political power.  Agamemnon causes the plague sent by Apollo because he wronged a priest by keeping the daughter of the priest as a concubine.  When Agamemnon demands that Achilles give him a replacement concubine, Achilles becomes very upset, and calls Agamemnon on his lack of warrior status, and insults his leadership abilities.  This quarrel sets up the framework for the rest of the Iliad.
Menelaus: Brother of Agamemnon.  Together the brothers are referred to as the "Sons of Atreus."
Patroclus: Patroclus is Achilles best friend.  Patroclus is intensely loyal to Achilles, and so it hurts him when Achilles leaves the fighting, because Patroclus can see the conflict within Achilles.  Patroclus is foolishly loyal, and persuades Achilles to lend him his armor so that Patroclus can rally the Greeks in the guise of Achilles, without Achilles actually fighting.  However, Patroclus is killed by Hector, the most significant Trojan warrior.  Achilles dies in spirit when Patroclus dies, and so he returns to battle, single-minded to destroy Hector and the Trojan army.
Odyssueus: An intelligent and crafty Greek soldier.  He is a brave fighter, but his strength lies in his wit and his lack of conscience.  Odysseus makes a bold trip into the Trojan camp at night with Diomedes, and kills many and gathers information.  This is the same Odysseus featured in Homer's "Odyssey," but here he is much younger and of lesser importance.
Diomedes: Odysseus' best friend, and an excellent fighter. 
Nestor of Pylos: Nestor is an older nobleman, and is much like a grandfather to the younger warriors.  Nestor functions as a kind of comic relief, and his speeches tend to ramble on for many pages.  However, he is significant because of his understanding of the terrible nature of war and his tempered wisdom and views because of his age and experience.
Calchas: Calchas is a prophet.  He acts as a mediator between mortals and Gods, and is the one to make Agamemnon aware of Apollo's reason for sending the plague.  However, Calchas is rarely listened to, because his news is often unpleasent.  His advice and foresight tend to be correct, but he is not respected. 
The Trojans: Allied with the Lycians, Illium refers to the city of Troy
Priam: Priam is the king of Troy. He is an old man, and is frail and weak due to the ten-year siege of the Greeks on his city.  He knows that his city will fall, and this makes him a broken man, even before he loses his son Hector.
Hector: Hector is the last hope for Troy.  He is the Trojans best fighter, and rallies the Trojan army many times.  Hector battles Patroclus when Patroclus is in Achilles' armor, and Hector kills him.  This dooms Hector, because Achilles becomes intensely wrathful in his desire for retribution.  Hector bravely faces Achilles instead of running like his brother Paris often did, and is successful for a short time due to the guarding of Aphrodite.  However, to the will of Zeus, she tricks Hector into thinking that he is divinely protected and invincible, and when she abandons him, Achilles is free to kill Hector.  Due to Achilles' rage, Hector's body is treated with vicious brutality even after he has died. 
Paris: Paris is Priam's son and Hector's brother. He is vain and foolish.  He tries to fight a few times, but is always ineffective, and is always rescued by Aphrodite.  Paris is the direct cause of the Trojan war, because he sailed to Greece and kidnapped Helen, the most beautiful woman.  Paris has no accountability, and it is tragic that he is the cause for many years of suffering and death on both the sides of the Greeks and the Trojans.
Andromache: Andromache is the wife of Hector.  She has recently had a son, and she begs Hektor to refrain from fighting on behalf of his son, as well as herself.  Hector makes a moving speech, the last time he will see his wife, where he talks about facing destiny and not hiding from it.  The love between Andromache and Hector is very strong, but eventually she cannot keep Hector from his destiny.