Your Foes Are Numbered
When a plot revolves around defeating a band of unique foes, said foes are often identified by number.
In action-based works, it's not uncommon for the protagonists to have to deal with a Quirky Miniboss Squad or Carnival of Killers at some point: a band of unique and memorable foes which serve as major antagonists for an arc or even the entire story. In many cases, these foes will be identified by numbers along with their proper names, which somehow both highlights their uniqueness and brands them as belonging to a particular group or organization.
- In One Piece, male agents of Baroque Works are identified by number; sometimes by name, as well, as per "Mr. 2 Bon Clay."
- The Espadas of Bleach are all purportedly numbered in order of strength, with lower numbers indicating stronger Espadas. This comes to a head when the 10th Espada, Yammy, is revealed to be the 0th Espada and thus the strongest. An exception would be the Espadas with numbers in the hundreds, which are ranked such as a mark of disgrace rather than as a designation of their relative power level.
- The Gung-Ho Guns of Trigun are each identified by number, as well as their name and title.
- In No More Heroes, members of the UAA each receive a numbered rank; ascending in rank typically involves killing UAA members who are ranked higher.
- Yu-Gi-Oh! ZEXAL centers around the Numbers, 100 powerful Xyz Monsters formed from Astral's lost memories. They have the power to possess and corrupt Duelists, and it falls to protagonist Yuma Tsukumo to recover them by defeating their holders. His rival Kaito Tenjo is also after the Numbers for his own reasons, however, and he's not as subtle in his methods...
- The Felt from Homestuck are a band of fifteen time-twisting criminals themed after the numbered balls used in pool. Each one has a unique power, most of which are based off of some sort of pun relating to their number: for example, (four-leaf) Clover has unbelievable luck, Fin (a five-dollar bill) can track people like a shark, (six-sided) Die can kill people retroactively with his voodoo doll, Crowbar (the shape of the number seven) has a crowbar that can disable time-twisting effects, and Stitch ("in time saves nine") can heal or harm people with his dressmaker's dummies. Their leader and the most powerful member of them is Snowman (which looks like the number eight); in addition to being able to mutilate Spades Slick with nigh-impunity, killing her will actually trigger the end of the trolls' universe.
Hello, Unknown Troper. You'll need to get known to lend a hand here.