Numerical Theme Naming

A strange form of Theme Naming is to give characters names which either contain numbers, or which are numbers. Whatever this says about the characters' parents and/or author, it does make it easier to keep track of who's who.

Note that this only applies to proper names. For one who is given a number instead of a name, see You Are Number Six. For a more specific sort of numerical theme naming, see One Two Three Four Go and Seven Is Nana.

Anime and Manga

 * In Rumiko Takahashi's manga/anime Maison Ikkoku, set in a boarding house, the various tenants all have names that reflect the numbers of their rooms (Mrs. Ichinose and her son in room 1, or "ichi"; Godai in room 5, "go", and so on). Even characters that don't live in Ikkoku-kan have numbered surnames, e.g. Mitaka ("mi", 3), Nanao ("nana", 7), etc.
 * In the anime Gundam Wing, many characters (including the Five Man Band) have names based on numbers which are used by fans as abbreviations (e.g., '2' for Duo Maxwell). This naming scheme also serves as a shorthand for pairings in the fandom.
 * Just going with the primary cast: Heero = 1, Duo = 2, Trowa = 3, Quatre = 4, Wu Fei = 5, Zechs = 6, Noin = 9, Une = 11, Treize = 13, Miliardo = 1,000,000,000. Several minor characters carry the theme, and it even extends into sidestories like G-Unit/Last Outpost, where protagonist Adin's name also represents the number 1, just in a different language (Russian) than Heero's (Japanese).
 * Many names in Keroro Gunsou are shown as 3-numbered codes because the syllables sound like numbers. It's Japanese l33t-speak from around 1999, when the manga first came out. This makes for especially odd English titles.
 * All the major characters in Kamichu include a kanji for the numbers 1-4 in their surnames, plus Yashima's name using the kanji for 8.
 * The original Legendary Birds in Pokémon were Articuno, Zapdos and Moltres.
 * Takeshi's (Brock) younger siblings all follow numerical theme naming from Jirou (the second eldest) down to Touko (the tenth child), this is effectively tossed out in the dub where there's no real theme to their naming at all.
 * Sol Bianca has planets named Uno and Tres.
 * In Mamotte! Lollipop, all of the magical examinees follow this pattern. The first two examinees Nina (ni means 2 in Japanese) meets are Zero and Ichi (1 in Japanese), then San (3) and Forte (4), and so on. Their magical registration numbers also correspond with their names.
 * In Katekyo Hitman Reborn almost every character has a number that corresponds to their name. For example Gokudera is 59 (Go=5, Ku=9). Some other examples include Tsuna (27), Yamamoto (80), and Hibari (18).
 * The Numbers of Magical Girl Lyrical Nanoha StrikerS fall somewhere between this and You Are Number Six, having both numbers (1-12), and names that are their numbers in Italian. The two are used interchangeably.
 * The Warumo Dan from Mirumo de Pon!: Ichiro (1), Jiro (2), Saburo (3), Shiro (4), and Goro (5).
 * In Vampire Knight the two twins Zero and Ichiru (old japanese word for one).
 * Within the crew of Cowboy Bebop, the characters' names each hold a different number of letters from one to five. Spike, Faye, Jet, Ed, and Ein means 'one' in German.
 * In Change 123, the female protagonist's three Split Personalities gave themselves normal Japanese female names Hibiki, Fujiko and Mikiri, but all these names begin with numbers: "hi" = 1, "fu" = 2 and "mi" = 3. These three are also collectively called "HiFuMi", which also means "1, 2, 3".
 * The three Marui sisters in Mitsudomoe. All their names are spelled with the [number]-[kanji for "leaf"] combination. Mitsuba (three), Futaba (two) and Hitoha (one).
 * A minor character in Ookami San is modeled after Snow White, with the seven dwarfs represented by her seven younger siblings, all with this naming convention.
 * In Baggataway, the members of the lacrosse team all have a number in their name. Ichizaki Mutsuka (Ichi = 1), Kisaragi Nina (Ni = 2), the Santou sisters, Kanna and Yayoi (San = 3, Tou = 10), Amaai Shiho and Shihatsu Touko (Shi = 4), Gotou Satsuki (Go = 5) Mizushino Rokuna (Roku = 6), Nanase Fumi (Nana = 7), Yaegaki "Hachi" Kazuha (Hachi = 8), and Nagasako "Kuumin" Kumi (Kyuu/Kuu = 9). Finally, although the main protagonist, Utsugi "Sora" Shizuku, doesn't have one, the character for "Shizuku" can be confused at a glance with the one for 0 (雫 versus 零).
 * There's even another round of Theme Naming - all the team members have the name of a month in the traditional Japanese calendar incorporated somehow into their names, which also (mostly) corresponds with their theme number.
 * Higurashi no Naku Koro Ni has Miyo Takano and Professor Hifumi Takano. Hifumi can be written as 一二三 (123), Miyo can be 三四 (34), which continues the sequence. Would be a stretch, except that it's pointed out in the anime when the two characters first meet.
 * In Mai Hi ME, Yuuichi's name contains the kanji for "one". The other kendo club members' given names, as seen on nametags in episode 2, are Tamaji, Kouzou, Shirou and Gosaku -- containing the kanji for "two", "three", "four" and "five" respectively.
 * Manjoume's "Thunder" nickname in Yu-Gi-Oh GX came from him demanding everyone at North Academy refer to him by "Manjoume san da", the latter two being honorifics. Now given that san is also 10,000 in Japanese, this led to the following chant: ""Ichi (1)! Jyu (10)! Hyaku (100)! Sen (1000)! Manjyoume Sanda (10000)!"
 * Mahou Sensei Negima has Averruncus series: Primum, Secundum, Tertium, Quartum, Quintum and Sextum. Nii and Septendecim similarly fit.

Film

 * A Filipino film, Ang Tanging Ina has a mother of 12 name her children as thus: Juan, Gertudis, Dimitri, Porcia, Pip, Sixto, Seve(n)rina, Cate, Shammy ('siyam' being Filipino for nine), Ten-ten, and two unnamed baby twins.
 * The Matrix includes characters Cypher (zero), the One, Switch (two), Trinity (three), and Dozer (twelve).

Literature

 * In the book Merlin's Mistake one of the protagonists is named Tertius. His two brothers are named Primus and Secundus. It is mentioned their father wasn't very creative.
 * In JRR Tolkien's legendarium, the first three Elves to awake were called Imin, Tata and Enel, that is One, Two, and Three. Much later, we have Nelyafinwë, that is, Third Finwë (after his grandfather Finwë and his father Curufinwë...quite possibly in an attempt by said father to spite his own brother, yet another Finwë.)
 * In Animorphs Yeerk names seem to contain a "name" followed by a three-digit number; since Yeerks are born with hundreds of siblings, fans speculate this is their birth order. If the Yeerks are twins, the last digit is doubled (for example, Esplin 9466 primary of the Sulp Niar pool, twin of Esplin 9466 secondary of the Sulp Niar Pool). Higher-up Yeerks usually go by rank, which is also numbered, at least for Vissers and Sub-Vissers (i.e., Visser Three, Visser One).
 * In the Remnants series, the Blue Meanies / the Children are all named by the system (Number) (Positive adjective) (Geographic feature), i.e., "Four Sacred Streams," "One Divine Mountain."
 * In the Discworld Agatean names also work like this.
 * The male descendants of the House of Gaius in the Codex Alera are all named in this fashion: Gaius Primus, Gaius Secundus, Gaius Tertius et cetera. Curiously, the fifth is named Gaius Pentius rather than Gaius Quintus.
 * In Septimus Heap the titular character is the seventh son of a seventh son.
 * Septimus and Octavia of The Covenant of Blood, are somewhere between this and You Are Number Six mixed with Meaningful Rename. Their master renames all his slaves with ordinal High Gothic names. Maruc, Septimus' assistant, is trying valiantly to avoid becoming Nonus in the eyes of his masters.
 * In Neil Gaiman's Stardust, the King of Stormhold followed the ancient Roman method in the naming of his sons: Primus, Secundus, Tertius, Quartus, Quintus, Sextus, and Septimus. There's a daughter named Una, too. Had there been more daughters, they'd surely follow a similiar trend.

Live Action TV

 * The latest line of Kamen Rider series: Decade (10), Double (2), OOO (3) and finally, Fourze (4).

Theatre

 * The Adding Machine has Zero and his nearly identical friends, One, Two, Three, Four, Five and Six. Their equally uniform wives uniformly take their husbands' names.

Video Games

 * The last names of the characters in Time Hollow follow numbers 1-12.
 * Seth, from Street Fighter IV, has the codename I-5; the number '5' is equivalent to the roman numeral 'V', thus, Seth's "number" is related to the game he first appears in.
 * In Earthbound, the towns are named Onett, Twoson, Threed, and Fourside.
 * The Legendary Pokémon Articuno, Zapdos and Moltres.
 * And in Pokémon Black and White, we have Deino, Zweilous, and Hydreigon, which are one headed, two headed, and three-headed dragons respectively.
 * In non-legendaries, Doduo and Dodrio.
 * Would Mew and its clone Mewtwo count?
 * There's also Dugtrio, which is composed of three Digletts.
 * Chrono Cross has a mixture of Latin and Spanish numbers for the Vita boss: Vita Unus, Vita Dos, and Vita Tres. Yes, we are aware that Vita Unus is not proper grammar.
 * Gehn, villain of the second Myst game, Riven, and one of the novelisations, numbers everything he has control of, most notably his Ages, and the people in them. Because Riven is his Fifth age, much of his property within it has that number on it somewhere.
 * Terraformer ships in X3: Terran Conflict and Albion Prelude are given a four-letter designation that proves to be a number in base 16. Some examples: #deca (57,034 in base 10), #fade (64,222), #cafe (51,966).

Webcomics
"From the bottom up, we have Itchy (from ichi, Japanese for one), Doze (from dos, Spanish for two), Trace (from tres, Spanish for three), Clover (four leaf clover), Fin (slang term for a five-dollar bill), Die (six-sided die), Crowbar (from the crooked shape of a 7), Snowman (from the shape of an 8), Stitch (...in time saves nine), Sawbuck (slang term for a ten-dollar bill), Matchsticks (two straight lines, as in 11), Eggs (a dozen eggs), Biscuits (a baker's dozen), Quarters (quatorze, Spanish for fourteen), and Cans (quinze, French for fifteen)."
 * From the Homestuck Midnight Crew intermission, we have the Felt, a gang of billiards-themed thugs, who are named as follows (copy-pasted from the article proper):

Web Original

 * Tetras, from The Motley Two. Obsessed with the number four, has a fitting name (the prefix tetra-).

Western Animation

 * The American cartoon Codename Kids Next Door does this to some extent. The names of the main characters are a reference to their numbers. Nigel Uno / Numbuh 1 (uno = 1, Spanish), Hoagie Gilligan Jr. / Numbuh 2 (Jr. after a name = 2nd in the family to use such name; also, Gilligan was second in command of the Minnow on Gilligans Island), Kuki Sanban / Numbuh 3 ("sanban" = third, Japanese), Wallabee Beetles / Numbuh 4 (The Beatles = Fab Four), Abigail Lincoln / Numbuh 5 (Abraham Lincoln = US $5 bill), and the first names of Numbuhs 1, 3 and 4 are a reference to their country of origin (England, Japan, and Australia respectively), the first name of Numbuh 2 is another name for a club sandwich (perhaps a reference to his size), but the first name of Numbuh 5 is just a name, unrelated to her French national origin. (Although it does resemble Abe, as in Abraham Lincoln.)
 * Seven Little Monsters. The seven monsters all have numbers for names, and as a result if they hear any mention of a number above seven, then they will all immediately break into song about numbers higher than seven.

Real Life

 * Indonesian children sometimes get names based on numbers: Eka (one, pronounced ay-ka), Dwi (two, pronounced do-e quickly), Tri (three, pronounced tree), Catur (four, pronounced chah-tour), and Panca (five, roughly pronounced pahn-cha).
 * Japan has a similar scheme available for male given names; Ichirou ("One" + "Son"), Saburou ("Three"), and so forth. A Dead Horse Trope was to have Asian stereotype characters use a Blind Idiot Translation and refer to "Number-one Son".
 * That was pretty common in Ancient Rome for families with many children too. Quintus was a name for the 5th son, Sixtus the 6th, Septimus the 7th, etc. Oh, and while we're at it, the Indonesian example given uses numbers taken from Sanskrit, a language of more historical/cultural significance (the Indonesian equivalents would be Satu, Dua, Tiga, etc.).
 * Similarly, Jung Chang mentions in Wild Swans that her great-grandmother had the name Second Daughter.
 * This was popular in ancient Rome, with the third, fourth and fifth sons very frequently being named Tertius, Quartus and Quintus. Similar schemes have also been popular in Sweden, such as naming a third son "Trisse" or an eighth daughter "Ottilia". Naturally obsolete nowadays when few families have more than two children.
 * Oglala children got this as well:
 * Boys: Caske, Hepan, Hepi, Catan, Hake, Hakata, Cekpa
 * Girls Witokape, Hapan, Hepistanna, Wanska, Wihake, Hakata, Cekpa
 * Aztecs were named after the day they were born.