Gratuitous Iambic Pentameter

"Sometimes in works, there is a certain kind, who always have poetic forms in mind. In every situation—great or small— they can't resist the urge to rhyme at all. ''Though often plainer words would suit much better, Gratuitous Iambic Penta-MET-er."

An iamb is a pair of syllables where the stress falls on the second one - ba-DUM (if it goes DUM-ba it's a trochee). Pentameter is verse with five stressed syllables (tetrameter has four, heptameter has seven, etc), so iambic pentameter has five iambs (usually ten syllables, but odd unstressed ones at the beginning or end don't affect the meter much). This kind of verse is very common in Shakespeare, as in for example "Un-EA-sy LIES the HEAD that WEARS a CROWN" (Henry IV Part 2). This trope can apply to any poetic dialogue though.

Anime & Manga

 * The Fatima Fates sometimes lapse into iambic pentameter when delivering a prophecy in The Five Star Stories, though this may only be in the English version. What's strange is that Clotho's prophecy in Volume II has the rhyming couplet at the beginning rather than the end.

Comic Books

 * Taking this in a new and strange direction, the demon Etrigan in the DC Universe speaks in rhyme. This is taken by one of the Endless as a sign he has been promoted in the demonic ranks. And when Alan Moore wrote him, he actually did speak in iambic pentameter. One incarnation of him accidentally forgot to rhyme in haste, meaning it's a conscious effort on his part rather than automatically how speech comes to him.
 * An issue of "Excalibur" told from the point of view of Lockheed featured him flying around spouting bad rhyme. Which is interesting, as it's been suggested on more than one occasion that, being an alien life-form, his vocal apparatus just can't cope with English.
 * Played with in the miniseries Arkham Asylum: Living Hell when it turns out that not only do many demons speak in rhyme, anything not in rhyme is incomprehensible. Thus, the human/demon interpreter job is left to Humpty Dumpty, who speaks fluent Poetic.
 * In Shadowpact, it was revealed that rhyming demons are considered as part of the underworld's upper class and one has to earn the privilege to become one. However, it must be a lower rank than being (a) Lord of Hell, as Neron was furious to be promoted to rhyming demon. Yes, a lowering of rank is called being promoted. They're demons. The lower they are, the more powerful and evil they are. Yes, it's stupid. But they discuss it at length when Blue Devil got his demotion and started rhyming.
 * Garth Ennis's Hitman also played with this, with a lower ranking demon named Baytor who, due to his inability to rise in Hell's ranks, could only say, "I am Baytor!"
 * In another example of Neil Gaiman using this trope, the conversations between Dream and the young Shakespeare in The Sandman are actually in iambic pentameter. The character Nuala also briefly drops into iambic pentameter at one point.
 * Gaiman makes a hobby of writing poems in unusual verse formats that have fallen out of fashion, sometimes for centuries. The prevalence of them appearing in his comic work is pure Author Appeal.
 * In an early issue of The Sandman, Lucifer claims that various poetic styles have been fashionable amongst demons at different times, and currently it happens to be rhyming.
 * Another Alan Moore example - the title Anti-Hero of V for Vendetta occasionally speaks in iambic pentameter, as part of his theatrical masquerade and his celebration of literature long suppressed. Particularly apt since "V" is "5" in Roman numerals.
 * Another Alan Moore example: Witch Wench, a 17th-century superheroine (and member of the time-traveling League of Infinity) introduced during Moore's run on Supreme.
 * Alan Moore really loves his iambic pentameter; in the League of Extraordinary Gentlemen book The Black Dossier, the final passage features Prospero explaining at length (and in iambic pentameter) the importance of fiction. Makes sense, after all he is a character from Shakespeare.
 * It comes back in Century: 1969. There's really no excuse for why a punk rocker in a seedy nightclub is singing in perfect iambic pentameter.
 * A recent supplemental comic for the most recent comic incarnation of the Transformers explains Wheelie's habitual rhyming as due to a glitched translation device that only works reliably in rhyme.
 * In Fables spinoff Jack of Fables, Lady Luck speaks in Iambic Pentameter.
 * In Empowered, the Caged Demonwolf combines this with Sesquipedalian Loquaciousness and Purple Prose (also, thesaurus abuse) for some truly remarkable dialogue.
 * One professor in a story by Wilhelm Busch talks like this.

Film

 * A not-quite-famous example in cinema would be Rudy Ray Moore's alter-ego Dolemite.
 * The entirety of Sally Potter's Yes is spoken in rhyming iambic pentameter.
 * The musical Les Demoiselles de Rochefort (The Young Girls of Rochefort) has a scene in which everyone speaks in alexandrines (the classical French line and equivalent of the iambic pentameter.)
 * James Gunn told Lloyd Kaufman he wrote Tromeo and Juliet completely in iambic pentameter. He didn't, but there is a lot of it.
 * The medieval parts of Roger Corman's The Undead have much of the dialog in varying types of blank verse.

Literature

 * In the Ebenezum Trilogy by Craig Shaw Gardner, we are almost immediately introduced to a Big Bad rhyming demon named Guxx Unfufadoo. He can speak without rhyming, but as his power (defined very generically) grows with every rhyme, he almost never fails to rhyme. In the succeeding trilogy he joins the party in an Enemy Mine scenario, with a Malfunction Malady where sneezing fits prevent him from rhyming... so he only speaks in blank verse with a specific beat pattern (and hopes he doesn't reflexively end a verse in a rhyme and start sneezing).
 * The Lord of the Rings features Tom Bombadil, an enigmatic figure who speaks in iambic tetrameter and actually made the ring itself turn invisible.
 * In The Particolored Unicorn by John De Cles, all unicorns love to show off -- some speak Sanskrit, some recite poetry, in order to be impressive pets. Lifesaver, the titular unicorn, speaks in iambic pentameter. As with the Etrigan example above, he drops it at one point in his excitement.
 * In Poul Anderson's A Midsummer Tempest the dialog is pretty much entirely in iambic pentameter, mostly unrhymed.
 * The main character in The Wise Man's Fear by Patrick Rothfuss ends up spending some time in Fae, where most conversations seem to be carried out in rhyming couplets. It's implied that this is a somewhat whimsical form of amusement, rather than a natural speech pattern.
 * Lord Peter Wimsey keeps doing this unintentionally in Busman's Holiday. The other characters lampshade it.

Live Action TV
"Ryan Stiles: Spock, put the tribbles down and help me with the ship!"
 * Star Trek: The Original Series: One of the reasons Captain James Kirk's dialogue sounds so stilted or fake is that William Shatner insisted on using varying iambic and trochaic rhythms, presumably due to his Shakespearean training. It was even parodied on Whose Line Is It Anyway??

": I'm sorry, but you're not on the guest list.
 * Maldis, a two-episode villain on Farscape once took the form of a wizard who always spoke in iambic pentameter.
 * In the third season of White Collar, Conspiracy Theorist Mozzie has started knocking on Neal's door in iambic pentameter.
 * An entire episode of Moonlighting consisted of lines in iambic pentameter. For bonus awesome, it was a hilarious parody of The Taming of the Shrew.
 * Or, the scene with David, Maddie, and a hotel security officer all speaking in Seussian rhyming couplets:
 * That's because we're not guests. We're looking for a man with a mole on his nose.
 * A mole on his nose?
 * A mole on his nose.
 * [to Maddie] What kind of clothes?
 * [to David] What kind of clothes?
 * What kind of clothes do you suppose?
 * What kind of clothes do I suppose would be worn by a man with a mole on his nose? Who knows?
 * Did I happen to mention, did I bother to disclose, that this man that we're seeking with the mole on his nose? I'm not sure of his clothes or anything else, except he's Chinese, a big clue by itself.
 * How do you do that?
 * Gotta read a lot of Dr. Seuss.
 * I'm sorry to say, I'm sad to report, I haven't seen anyone at all of that sort. Not a man who's Chinese with a mole on his nose with some kind of clothes that you can't suppose. So get away from this door and get out of this place, or I'll have to hurt you - put my foot in your face."

"Ainsley: Mr. Tribbey? I'd like to do well on this, my first assignment. Any advice you could give me that might point me the way of success would be, by me, appreciated. Lionel Tribbey: Well, not speaking in iambic pentameter might be a step in the right direction."
 * One episode of the The West Wing had the president and staff wondering about the mental capacity of one of the Justices of the Supreme Court after he issued comments in Iambic Tetrameter, identified positively by the writing staff.
 * Ainsley Hayes apparently does this as a nervous tic, such as in this exchange from "And It's Surely to Their Credit":


 * In the 2000 Dune miniseries, the Baron Harkonnen was fond of speaking in rhyming couplets.

Theatre
"It's all so strange, What's even stranger though I speak in blank verse like the characters Unrhymed Iambical Pentameter It seems to come quite naturally to me I feel so eloquent and... eloquent. My God. I think I'm on an acid trip."
 * There is a very amusing scene in the play Goodnight Desdemona (Good Morning Juliet), where the main character, having been sucked into Othello, realizes that she is now effortlessly speaking in iambic pentameter.


 * Subverted in Molière's Le Bourgeois Gentilhomme, in which the title character, having learned that it is more elegant to speak in prose rather than affecting metre, is delighted to learn he has been speaking prose all his life without knowing it.
 * Gilbert and Sullivan's operetta Princess Ida has its dialogue in iambic pentameter.

Video Games
"This one is machine and nerve, and has its mind concluded. This one is but flesh and faith, and is the more deluded."
 * Legacy of Kain wouldn't be itself without this.
 * A video game example can be found Final Fantasy XII, where the immortals that muck about with history actually do, for the most part, speak in iambic tetrameter. The rebel of their number speaks in iambic pentameter.
 * This may be a reference to Shakespeare's Macbeth, in which the Witches speak trochaic tetrameter (four feet, alternating stress, starting with a stressed syllable) to help illustrate their otherworldly nature.
 * Bastian in Fire Emblem 9 speaks entirely in iambic pentameter. Elincia also uses it for a Rousing Speech.
 * This reoccurs in Radiant Dawn: the prince of Daein, Pelleas, once gives a speech that's mostly in this meter to his troops. Yet Bastian's verse is nowhere to be found.
 * In the Halo series, the Flood intelligence Gravemind speaks in rhyming couplets of trochaic heptameter (seven being Bungie's Arc Number). This pushes its already impressive hamminess Up to Eleven. For example, referring to Master Chief and the Arbiter,

"Gravemind: I have the memories of many poets far beyond your limited human culture. And I have the quickness of intellect to compose all manner of poetic forms as I speak rather than labor over mere words for days."
 * When Cortana asked it why it did so in Human Weakness, it simply said it was preference, as after having consumed many poets from different cultures, it grew fond of their gifts.


 * The elven hero Findan from Heroes of Might and Magic V speaks in various kinds of poetic metre. Many of his lines are haiku.
 * In Castlevania: Order of Ecclesia, every line Barlowe says between Shanoa losing her memory and is in iambic pentameter.
 * Vangers featured Eleepods - a race of fat and lazy worms obsessed with poetry. Their manner of speech also resembles blank verse, but this was Lost in Translation.

Webcomics

 * Xkcd has a strip featuring actual iambic pentameter.
 * Hibachi and the other dragons in The Inexplicable Adventures of Bob
 * Questionable Content has a library with a peculiar application process.
 * Ozy and Millie once had an iambic penslameter, where they poked fun at each other in iambic pentameter. Then Llewellen showed up and invited them to pie in iambic pentameter, which Ozy declared a coincidence; he always talks like that when baking pie.
 * One of the languages you can view the fancomic Darths and Droids in is "poetry".

Western Animation

 * Underdog speaks in rhyming couplets. Interestingly, his alter-ego Shoeshine Boy does not.
 * In the Hungarian translation of The Flintstones, everybody speaks in rhymes. Mind Screwing, indeed.
 * Wordsworth in Heathcliff and The Catillac Cats doesn't take the name of a poet for nothing.
 * Japeth the mountain goat in Hoodwinked can't talk, only sing, because of a curse. Except when he forgot. Exceee-e-e-eeept he di-i-i-iddy-iddy-idn't.
 * A really gratuitous example from the third Madagascar film: "You FOOL! How COULD you LET them GET aWAY!?"