A problem play by Creator/WilliamShakespeare, set during UsefulNotes/TheTrojanWar-- Shakespeare used ''Literature/TheIliad'' as a reference. It has been variously described as a tragedy, a romance, and a tragicomedy; its oddly opposite but interwoven A and B plots make it difficult to classify.

The A plot, which provides the play name, is a romance-- Troilus, a brave warrior and prince of Troy, is desperately in love with Cressida. She returns his feelings, but is playing hard to get. Troilus uses Cressida's scatterbrained uncle, Pandarus, as a go-between; as a result, Pandarus spends most of the play singing Troilus' praises (and making bawdy jokes). Eventually, Troilus woos her and they consummate their relationship. However, Cressida's father, who defected to the Greeks, exchanges her for a Trojan soldier, and so the lovers are separated. Troilus asks her to be faithful, and gives her a love token (sleeve) to remember him by. He can't bear to be apart from her, though, so when everyone gathers for a duel between the two sides (see below), he goes to visit her. He discovers, however, that she has been seduced by Diomedes, a Greek warrior. In an extended scene, he and Ulysses watch secretly as she betrays him. Infuriated, Troilus decides to kill some Greeks, yells at Pandarus, and leaves the old man wondering what he did wrong.

The B plot is more serious, and concerns the war, borrowing heavily from Creator/{{Homer}}. Agamemnon, the Greek general, is upset that [[AchillesInHisTent Achilles is sulking in his tent]] and won't fight the Trojans. Ulysses and Nestor concoct a plan to get Achilles to return to battle: instead of using Achilles as their champion in a duel proposed by Hector of Troy, they send out strongman Ajax. This, they hope, will infuriate Achilles into fighting. Ajax boasts and beats up his extremely rude servant, Thersites, who snarks crassly at everyone. The duel falls through, though it serves to goad Achilles to return to the battlefield in order to fight with Hector himself. The two meet on the battlefield the next day, but Hector drives off the Greek hero. Achilles later gathers his loyal soldiers and ambushes an unarmed Hector. They kill the Trojan prince, an act for which Achilles claims the all of the glory.

An odd thing about ''Troilus and Cressida'' is that it doesn't end so much as stop. The drama between Troilus and Cressida, which is built up through the entire play, is never resolved; Troilus just storms off stage, and the play ends. Also, in defiance of Shakespeare's other tragedies, Troilus doesn't die at the end. The jarring juxtaposition between the political B plot and the romantic A plot is equally notable.
!! ''Troilus and Cressida'' provides examples of:

* AchillesInHisTent: Literally.
* AdaptationDeviation: It's clear that Shakespeare didn't care about sticking to the original Iliad and the way the characters are depicted shows it. The UnstoppableRage Achilles goes into in order to avenge Patroclus is severely altered and the play instead has Achilles sneaking up on Hector while he sleeps. Which kinda defeats the purpose of the story being about glory in war.
** Hector died in the ninth year of the Trojan War, the play takes place in the seventh.
** Troilus was killed by Achilles years prior to his battle with Hector. The event is hinted at in the Iliad.
** Calchas was not a Trojan defector, he was a Greek full and full.
** Antenor was not general, he was an adviser to Priam.
* AnachronismStew: Hector mentions Aristotle at one point... centuries before he lived. This line is even more ridiculous when you realize Aristotle actually taught about the Trojan War and was a scholar on Homer. This line is so stupid some scholars actually think a later editor must have put it in. Though given many other fairly obvious anachronisms are present in Shakespearean plays this likely just another dumb mistake on Shakespeare's part.
* BadassGrandpa: Nestor is old as dirt, but said to be still as capable a soldier as he ever was.
* BerserkButton: Achilles does not take kindly to Patroclus' death.
* CassandraTruth: With the original Cassandra!
* CharacterExaggeration
* CharacterFilibuster: If Ulysses is speaking, there's a good chance it's going to be a two-page speech.
** Subverted when he's about to launch into another speech, and Cressida cuts him off after two lines of PurpleProse.
* CompositeCharacter: Other characters mention that Ajax is half Trojan, and that his mother was Priam's sister. In ''Literature/TheIliad,'' Ajax is simply a Greek warrior, but his half-brother Teucer (who also fights for the Greeks) is the son of Priam's sister who was taken prisoner during an earlier invasion of Troy.
* DarkerAndEdgier: Could be considered this for ''Literature/TheIliad.'' While the original is full to bursting with great Greek heroes doing great deeds, the play is a portrait of two armies mired in decadence, lechery, illness, violence, and corruption, where even young love turns sour and the final image is a syphilitic Pandarus promising to [[{{Squick}} "bequeath you my diseases."]]
* DoingInTheWizard: The gods do not appear.
* DumbMuscle: Ajax, whose lines tend to come in the form of short, uncomplicated prose exclamations. He would rather resort to violence than speech. Thersites mocks him mercilessly for it in their first scene.
-->'''Thersites:''' Thou sodden-witted lord, though hast no more brain than I have in mine elbows; an asinico may tutor thee. Thou scurvy-valiant ass, thou art here but to thrash Trojans, and thou art bought and sold among those of any wit like a barbarian slave.
* GetTheeToANunnery
* GoodIsDumb: Noted as one of Hector's character flaws.
* HonorBeforeReason: The reason they ultimately all meet a tragic end is because they refuse to do what is feasible, and instead seek to uphold their honor until death. Hector, notably, is chastised by his brothers for frequently showing mercy to defeated Greeks. He receives none from Achilles and his Myrmidons.
* JerkassHasAPoint: Thersites may spout a whole lot of incendiary language, but he makes some fair observations about both sides and the war as a whole.
* LovedINotHonorMore: Hector, when his wife Andromache begs him not to fight:
--> "Life every man holds dear, but the brave man
--> Holds honor far more precious-dear than life."
* LoveTriangle
* TheMatchmaker: Pandarus tries his best to be one between Troilus and Cressida.
* MoodWhiplash: The romantic plot between Troilus and Cressida, which is busting with sexual puns, and the serious story about war between the Greeks and Trojans.
* NameAndName
* NonActionSnarker: Thersites.
* {{Pungeonmaster}}: Pandarus, with sexual puns. Helen and Paris, too, come to think.
* QuestionableConsent: Cressida is a Trojan woman in a Greek war camp. [[SarcasmMode Yeah, she is completely in control of her situation]].
* {{Revenge}}: The reason Achilles finally leaves his tent.
* RoaringRampageOfRevenge: What happens once he does.
* SadlyMythtaken: Cressida is such a common part of modern perceptions of the Trojan War it may come as a surprise that she is not a part of Greek Mythology. She instead a Renaissance invention derived from the two maidens Achilles and Agamemnon quarrel over, Briseis and Chryseis, making her an example of CompositeCharacter and AdaptationDecay.
* SesquipedalianLoquaciousness: Ulysses. In his first speech (which is [[CharacterFilibuster 62 lines long]]), he uses "vizarded," "deracinate," and "oppugnancy." That's fancy even for Shakespeare.
* SexualExtortion: Related to QuestionableConsent, Diomedes basically gives Cressida the choice of being his woman or everyone's woman.
* ShoutOut: To Marlowe
* SlidingScaleOfIdealismVersusCynicism: ''Waaaaay'' on the cynical end. Arguably Shakespeare's most cynical play. Troilus just giving up, rather than dying heroically, is of course part of this.
* StillTheLeader: Agamemnon is determined to invoke his rank if the troops aren't going to obey him of their own volition, even if he is no longer respected.
* TheStoic: Ajax, who is parodied by Thersites in this aspect.
* WhatYouAreInTheDark: Even Hector behaves badly when no one is watching.