Troilus
Troilus is the protagonist, and half of the titular couple. He is a Trojan prince, warrior, and son of King Priam. In the beginning of the story, we see Troilus as being quite naïve in matters of love, even mocking his knights when they develop feelings for women. As a result, he is struck by Cupid and falls instantly in love with Criseyde. From here, he becomes single-mindedly focused on winning her over as his lady. Troilus' inexplicable love for Criseyde transforms and humbles him, influencing him to become a more chivalrous, honorable, and mature man who realizes the true value of love as a divine force.
Yet for all of his virtues, Troilus struggles with extreme emotions and lovesickness throughout the story. He becomes almost addicted to Criseyde and relentlessly pushes the relationship forward to the point of being somewhat forceful and manipulative, not able to take no for an answer. When fortune is in his favor, Troilus is blissful; when bad luck strikes, he curses his existence. This instability is eventually what ruins the soldier, causing him to spiral into desolation after being betrayed by Criseyde. Ultimately it is left up to the reader to decide if Troilus is a hero or fool; if his actions are motivated by true love or utter madness.
Criseyde
Criseyde is a beautiful young woman in Troy and the daughter of the traitor, Calchas. Criseyde is Troilus’ lover but her character is much more complex than this role alone. She is initially reluctant to embark on the relationship with Troilus, and intelligently considers the effects an affair will have on the freedom she currently has as a widow. Yet slowly she opens her heart to Troilus and begins to admire his noble qualities. In Book 3 it seems especially as if she is equally smitten as her partner. Yet when the two are forcibly separated, Criseyde cannot live up to the vows of union she made.
Criseyde may easily be criticized for her betrayal of Troilus in Book 5, but Chaucer is careful to not paint her as all evil or heartless. Rather we are shown the complexity of Criseyde's situation and even encouraged by the narrator to have empathy for her. On one hand, Criseyde undergoes much grief and struggle as she chooses Diomede over Troilus. On the other hand, we are shown that she is not always honest and does somewhat manipulate Troilus, such as when she falsely suggests that it is he, not she, who has been unfaithful to her. Moral impeccability she may not have, but as a woman in Ancient Greece we are made to sympathize with her desire for safety and good standing over uniting with Troilus.
Pandarus
Pandarus is Criseyde’s uncle, and the only male presence in the young maiden's life. He is also Troilus’ loyal friend, confidante, and advisor. He has been previously described as a "secondary" narrator, prompting plot points to occur and pushing characters into action. He orchestrates almost all of Troilus and Criseyde’s love affair, from manipulating Criseyde into agreeing to meet Troilus, to physically pushing the two lovers into bed together. Pandarus is nearly as invested in the relationship as Troilus, even telling Criseyde he will kill himself if she doesn't accept Troilus' advances.
When Criseyde and Troilus are separated, Pandarus acts as a counselor and often soothes Troilus in his bouts of sorrow and uncertainty. In his attempts at comforting his friend, Pandarus sometimes distorts the truth—not only to alleviate Troilus' suffering but also to avoid any potential blame for Troilus' heartbreak, as he has been the architect of the entire relationship. For example, Pandarus denies the obvious meaning of Troilus' boar dream, not wanting to acknowledge that Criseyde has, in fact, been unfaithful.
Diomede
Diomede is a Greek soldier that offers his friendship and protection as soon as he meets Criseyde. Diomede is described as a brute, assertive, and masculine warrior. Not long after Criseyde's arrival at the Greek camp, Diomede begins to woo the lady and convince her of his qualifications as a partner. It can be interpreted that Diomede is not truly in love with Criseyde but desires her out of a sense of dominance and competition; while bragging of his virtues, he repeatedly tells her that Greek men are better than Trojans. Troilus is enraged when he discovers Diomede is Criseyde's new lover, and later spars with him on the battlefield.
The Narrator
The narrator is somewhere between a character and the author of the story, Geoffrey Chaucer. He is present at the start of each book in the proems to the gods and regularly interjects his viewpoint. He especially makes himself known in the pivotal moments of the plot, such as when the couple finally unites and when Criseyde betrays Troilus. He is sympathetic to Criseyde despite her infidelity and encourages the reader to forgive her. At the start of the first book, the narrator proclaims himself unworthy of love. Otherwise, we know little of the narrator's character.
Calchas
Calchas is Criseyde’s father and a soothsayer. Early in Book 1, he predicts that Troy will fall to the Greeks and deserts the Trojans for the Greek camp, thus becoming a traitor. This leaves Criseyde vulnerable and alone in Troy, where she is looked after by Pandarus. Calchas is also the one who orchestrates the exchange of Antenor for Criseyde. Although a minor character, his actions spark the separation of the lovers and Criseyde's eventual betrayal of Troilus.
Hector
Hector is the brother of Troilus and Paris, and a son of Priam, the Trojan king. Criseyde initially appeals to him for protection, and he comes to her aid. He later dies in battle during the destruction of Troy.
Deiphebus
Deiphebus is Troilus’ older brother and the character who arranges for Troilus and Criseyde to meet for the first time at his house.
Antenor
Antenor is a Trojan lord captured by the Greeks. He becomes relevant when Calchas arranges for Antenor to be exchanged for Criseyde, meaning Criseyde must leave Troy.
King Priam
He is the King of the Trojan state and the father of Troilus. Much to his son's lament, he approves of sending Criseyde to the Greek side.
Cassandra
Cassandra is Troilus' sister who correctly interprets his dream of the boar as an indication of Criseyde's betrayal.