Sakuya Izayoi (EntityTopic, 12)
From Compile Worlds
Sakuya Izayoi is a freakin awesome maid who works in the Scarlet Devil Mansion in Embodiment of Scarlet Devil. It's worth noting that she definitely doesn't wear pads and if you try to say she does she will probably assassinate you. Quite why she works for Remilia is not known but many fans believe there is something between them.
Like Knuckles and his Master Emerald she apparently temporarily gives up her important job to fly around Gensokyo as a playable character in later games.
She also has the most kickass theme ever, fitting for how awesome she is.