The Nijiura Maids are characters of the Futaba Channel japanese imageboard (specifically Nijiura, as the name suggests.) They are a collection of maid characters most of whose personalities are based on puns involving their names. The first of these, Medoi-san's name is a pun on "meido", the japanese pronounciation of the english word "maid". Medoi is slang for "bother", so Medoi-san finds everything to be a bother. Most of the rest follow a similar pattern.
These characters may not fall into the traditional Nijiura Maid template, but they are maid characters thought up by Nijiura residents and are often seen in conjunction with the other maids.
A set of maids known as the Nijiura Chinese Maids (虹裏中華メイド庫) They are primarily based on Chinese constellations and mythology. I'm not sure if it merit a separate tag in addition to the basic nijiura maid one, but yeah. We'll probably need to make new tags for those that currently have other unrelated posts on their name's tag, but that can happen later.
Note that in all cases, these character's names are the Japanese equivalent of the Chinese creature they're based on (as opposed to the original Nijiura maids, whose names are often based on word combinations or puns.)