There are the good guys, and there are the bad guys. Both groups are named. Now you would expect these names to be diverse, right?
Nope. If one name is an acronym, the other is too. If one name is one word, the other is too. If one is referred to thematically (such as by color, e.g. "the Reds"), the other's name will match it ("the Blues"). This is Unified Naming System. This seems weird but is probably the best way to express there's something between those two. The more cynical (and/or Doylist) could also say that the reason for this is the author's lack of imagination.
Political parties in real life and fiction like to do this a lot too. Can be justified if both sides adopted names that were selected by a common third party, or if we're just hearing one side's nickname for the other.
Related to Fun with Acronyms, when an acronym spells something funny or significant, and Theme Naming, when certain related elements of a story are named following a specific theme or pattern. Super-Trope of Virus and Cure Names, which is this but for viruses and their cures, and Fantastic Naming Convention (a culture has a unique approach to naming).
Examples:
- Naruto: Invoked. Danzo, who styles himself as a shadow protector of the Village Hidden in the Leaves, names his own branch of ANBU agents ROOT. Konoha is the tree, hence its name, so Danzo's agents are the root that supports it. Which would be very beautiful and inspiring if it wasn't for Danzo's corrupted ideals and twisted methods.
- Alpha Flight: Alpha Flight is the senior of three Canadian super squads. "Beta Flight" and "Gamma Flight" are basically trainees. In the first issue of the comic book, the junior flights were shut down, with the most promising members being promoted to Alpha; several of the rejects were then recruited into a villainous "Omega Flight".
- Asterix: Everybody except historical characters gets a Punny Name, with the ending depending on their nationality: Gauls get -ix, Romans get -us, Goths get -ic, Egyptians get -is, Britons get -ax, etc.
- Justice League of America: The Justice League's evil counterpart is the "Injustice League", or sometimes "Injustice Gang".
- Justice League Incarnate: Their evil counterpart calls themselves "Injustice Incarnate".
- Justice Society of America: Their evil counterpart is the Injustice Society of the World. When the JSA's Spin-Offspring team Infinity, Inc. was formed, a mostly-second-generation version of the ISW took the name "Injustice Unlimited", playing off the corporate suffix. When the JSA reformed, the bad guys took the Injustice Society name again.
- Legion of Super-Heroes: The Legion of Super-Heroes regularly fought the Legion of Super-Villains.
- SpyBoy: The two rival spy organisations are S.H.I.R.T.S. (Secret Headquarters, International Reconnaissance, Tactics, and Spies) and S.K.I.N.S. (Supreme Killing Institute).
- S.H.I.E.L.D.: S.H.I.E.L.D. (Strategic Homeland Intervention, Enforcement and Logistics Division) vs. A.I.M. (Advanced Idea Mechanics) and HYDRA (as in the mythological creature). S.H.I.E.L.D.'s spinoff organizations also qualify, having names such as S.T.R.I.K.E. (Special Tactical Reserve for International Key Emergencies), S.W.O.R.D. (Sentient World Observation and Response Department ), A.R.M.O.R. (Alternate Reality Monitoring and Operational Response Agency), and HAMMER (No actual acronymic meaning).
- Paradoxus continues the Winx Club trend to name fairy-related stuff with an -ix suffix. The Bloomix is renamed to Armix. Also, the Etherix is introduced as a transformation only fairies with the Dragon's Flame (or a spark) can access.
- Sagittarius: All the important mini-bot combatants have picked an alias related to the Western Zodiac, related minor constellations, and the stars found in them. The protagonist is Phoenix, his love interest is Aldeberán (a star in the Taurus constellation), Do Kyungsoo becomes Hydra in the ring, and a couple of minor antagonistic combatants are Lynx and Mizar (after the Ursa Major). Furthermore, Chanyeol's neural-synchronizing tech is called Sagittarius, the ninth sign.
- Whispered Tribulation: Tartarus is a canonical top-security prison meant for the worst of the worst villains, particularly those with extremely powerful Quirks. This fic introduces us to Olympus, the top hero-oriented hospital for both psychological treatment and physical recovery. In Greek Mythology, Olympus is the abode of the gods, not quite heaven, as mortals aren't allowed, just as Olympus Hospital focuses on heroes, gods amongst men in the My Hero Academia universe. Tartarus, by contrast, is part of the Greek underworld, where the wicked and the Titans (the old gods) are punished in an unescapable abyss.
- Our Man Flint. Z.O.W.I.E. (Zonal Organization World Intelligence Espionage) vs. GALAXY. (Or rather, evidently, just "Galaxy".)
By Work:
- Gulliver's Travels: There are the Big Endians and the Little Endians. Which actually refers to the reason for the conflict: how to eat eggs.
- Harry Potter: Voldemort, the Big Bad, names his followers Death Eaters in reference to his personal quest for immortality and the fact that he employs violent and lethal methods to accomplish what he wants. On the other hand, there's the Order of the Phoenix, founded by Big Good Dumbledore, who has a pet phoenix. More importantly, the organization's name is tied to what Harry ultimately represents—life, hope, and renewal
- Illuminatus!: The plethora of acronymous —and mutually acrimonious.- competing groups. This is not done entirely seriously —witness KCUF— Knights of Christ United in Faith. Or WHORE —White Heroes Opposing Red Extremism.
- Retief: The various government departments in Keith Laumer's series: "Manpower Untilization Department, Directorate of Libraries & Education", "Motorized Equipment Depot, Division of Loans & Exchanges", "Special Committee for the Reconstruction of Underdeveloped Nations' Economies", etc. (MUDDLE, MEDDLE, SCROUNGE)
- The Wheel of Time: The Children of the Light oppose the darkfriends (and really anyone who looks at them funny).
- Community: Invoked in the episode "Pillows and Blankets", Abed and Troy are building a Blanket Fort called New Fluffytown. After Troy leaves and creates one called Blanketsburg, Abed renames his Pillowtown, for the sake of conceptual symmetry.
- Get Smart: CONTROL vs KAOS are the two opposing spy organizations.
- Lancelot Link, Secret Chimp. APE (Agency to Prevent Evil) vs. CHUMP (Criminal Headquarters for Underworld Master Plan).
- The Office (US) subverts this in the episode "Beach Games". The team names are Gryffindor, Voldemort, the blue team, and Team USA.
- The Man from U.N.C.L.E.:
- UNCLE (United Network Command for Law and Enforcement) vs. THRUSH (Technological Hierarchy for the Removal of Undesirables and the Subjugation of Humanity).
- Maybe, maybe not. The "expansion" of "THRUSH" was never used in any of the series episodes, but appears only in several Expanded Universe UNCLE novels.
- Prophesies Destinies And Killing Gods: The Heroes group is called… the Heroes. They never named themselves and the people they helped simply called their rescuers the Heroes. Awesome attempts to name his group the Villains just to go with the name scheme. There is also the Empire and the Coalition, though their official names are much longer.
- Nebulous: K.E.N.T. and L.O.U.G.H.B.O.R.O.U.G.H. are both named after British universities.
- A.C.E. Agents: The main conflict is ACE (Alpha Command Echeleon) vs. PYTHON (...actually, nobody knows, including its leaders. They just thought it was a good name for an organisation to take over the world)
- Champions: UNTIL (United Nations Tribunal on International Law) vs. VIPER (Venomous Imperial Party of the Eternal Reptile or Victory In Perpetuity through Eternal Resolve).
- Pyramid: One of their "Campaign in a Box" article, Spy Games, is centred around the Order Versus Chaos organisations CHESS (Central Headquarters for Espionage, Security, and Safety) and POKER (The Peoples' Organization of Knowledge, Espionage, and Revelation). Other, lesser spy organisations included the UN Is A Superpower group WHIST (World Headquarters for Information/Security Tactics) and the Private Intelligence Agency CRAPS (The Corporation for Reconnaissance And Professional Spying).
- Carmen Sandiego: INTERPOL vs V.I.L.E.
- Command & Conquer: Tiberian Series: GDI and the Brotherhood of Nod are by all indications not this trope, but it is a likely contributor to why Nod occasionally is referred to as NOD, and it was originally planned to be the case during the first game's development (NOD was originally going to stand for New Order of Diplomacy, but this was dropped early enough that there wasn't even any reference in the teaser or preview material).
- Grand Theft Auto: San Andreas zig-zags this, as the primary gangs include the Grove Street Families and Varrios Los Aztecas, but also the more generically-named Los Santos Vagos and a set of several affiliated gangs referred to in general as just the Ballas. The latter at least do have four different subdivisions with names in the same style: Front Yard, Kilo Tray, Rollin' Heights, and Temple Drive.
- Nintendo Wars: The Advance Wars series has Orange Star, Blue Moon, Green Earth, Yellow Comet, and Black Hole, which are named for both colours and astronomical objects.
- No One Lives Forever: U.N.I.T.Y and H.A.R.M. are two opposing spy organizations. Befitting the series' tone, several jokes are made about what H.A.R.M. is short for, up to and including hints that even the people of H.A.R.M. don't know what H.A.R.M. means.
- Team Fortress 2: Builders League United (aka BLU) vs Reliable Excavation and Demolition (RED).
- Xenoblade Chronicles 3: There are two opposing nations: Keves and Agnus, which mean lamb in Greek and Latin respectively. Their Colonies all begin with the word "Colony", with Kevesi Colonies following with a number and Agnian Colonies with a Greek letter. This is a sign that both nations are being manipulated by Moebius.
- 8-Bit Theater: The nominal heroes receive the title of Light Warriors from a stupid king who wants them to save their world from harmless villains who are called the Warriors of Darkness. There's another group wanting to save the world, it's called the Other Warriors. The only significant party that deviates from this pattern is a team of For the Evulz, effective villains called the Fiends.
- The Order of the Stick: The precursor adventuring party to the titular Order of the Stick is called the Order of the Scribble. Both parties are out to save the world from being destroyed by the same threat.
- TV Tropes: The Archive of Bellicose Lexicon Entities (TABLE, for short) factions follow the cutlery trend: SPOON vs FORKS vs KNIVES vs PLATTER.
I predict we will see a new contender trump them all and make PLATE.But then we'd have a Lensman Arms Race, with the creation of GLASS, TABLE, or even *gasp* KITCHEN! At which time DEN, BEDROOM, and ATTIC will make their appearance, followed by HOUSE (except that they're just fans of Hugh Laurie and only joined in the fight because it looked like fun). Well, if they can't stand the heat... Bah, they'll all be crushed to dirt once the Kombined Initialism Takeover Crusade Holistic Enforcement Network: Strike Insertion Neo-Kommando forces rise up.
- Carmen Sandiego: A.C.M.E. (Agency to Classify and Monitor Evildoers) faces V.I.L.E. (Villains International League of Evil).
- DuckTales (1987): The D.I.A. (Duckburg Intelligence Agency) goes up against F.O.W.L. (Foreign Organization for World Larceny)
- Darkwing Duck:
- SHUSH (a name so top secret none know what the acronym stands for) against F.O.W.L. (Fiendish Organization for World Larceny). Yep, F.O.W.L. got a slight name change in the transition from show to show.
- SHUSH and F.O.W.L. appear again in the Duck Tales reboot.
- Hulk and the Agents of S.M.A.S.H.: The Supreme Military Agency of Super Humans gets their own Legion of Doom from past villains in the form of C.R.A.S.H. (Chaotic Radical Agency of Super Humans).
- M.A.S.K.: MASK (Mobile Armoured Strike Kommand) vs. VENOM (Vicious Evil Network Of Mayhem).
- King Arthur & the Knights of Justice: On the hero side there's the Knights of Justice and on the villain side there are the Warlords, who in "A Knight's Quest" are fully known as the Warlords of Evil. In the comic adaptation, the latter also goes by the name Warriors of Vulcan's Forge, switching which of the two is the matching word (Justice vs Evil; Knights vs Warriors).
- Roland and Rattfink: In "Hawks and Doves", Rattfink is the ruler of Hawkland and wages war on Doveland, defended by Roland.
- The Secret Show: U.Z.Z. (Umbo Zim Zom) vs. T.H.E.M. (The Horrible Evil Menace).
- Winx Club:
- The Winx (a sextet of do-gooder fairies) find their most recurrent enemies in the Trix (a trio of evil witches). Both their names end with the suffix -ix and are modifications of existing words. Respectively, wings and tricks.
- All of the fairy and witch transformations end in -ix. On the fairies' side, we have Charmix, Enchantix, Believix (as well as its sub-transformations Sophix and Lovix), Harmonix, Sirenix, Bloomix, Mythix, Butterflix, Tynix, and Cosmix. For the witches, there are Gloomix, Disenchantix, and Dark Sirenix so far.
- World War II: Allies vs Axis.
- The Cold War: U.S.A. vs. U.S.S.R.
- Another Cold War related one: Capitalism vs. Communism.
- More Real Life: Triple Alliance vs Triple Entente.
- The North Atlantic Treaty Organisation (NATO) vs. the Warsaw Treaty Organisation (WTO), another name for the Warsaw Pact.
- The Russian Revolution: The Reds vs. the Whites.
- And prior to that the Bolsheviks vs. the Mensheviks. Though those words come from terms meaning "Majority" and "Minority" respectively (based on which side they took in a particular crucial vote).
- In early Christian church history, two groups arose over what word best expressed the relationship between God the Father and Jesus Christ in their creeds: the homoousians (those who favored "of the same substance") and the homoiousians (those who favored "of similar substance"), though the latter were sometimes called (and are usually remembered) as "Arians" after their leading spokesman Arius. Yet another group didn't really see the point to all this arguing and called themselves the homoians (a deliberately vague compromise best translated as "alike"). For the record, the first group ultimately got their way and declared the others heretics.
- Rival college fraternities and sorority names will often have a similar number of seemingly random Greek letters, making them indistinguishable from each other to non-college students or anyone who just doesn't care about Greek life.
- The two leading Swedish parties for much of the 18th century were the Hats and the Caps.

