Scullery Maid

And then she went on and on till she came to a great house.
"Do you want a maid?" says she.
"No, we don’t," said they.
"I haven't nowhere to go," says she; "and I ask no wages, and do any sort of work," says she.
"Well," said they, "if you like to wash the pots and scrape the saucepans you may stay," said they.
So she stayed there and washed the pots and scraped the saucepans and did all the dirty work.

—Cap O'Rushes

Your less-developed fantasy worlds will contain no castle underlings save guards and kitchen staff. The guards lead a sad existence as Red Shirts, but the latter option presents a marvelous opportunity for anyone willing to submit to a little drudgery, if she can only get herself placed as a Scullery Maid.

If she's in for infiltration, scullery maids (or any other menial help staff) are practically invisible. They don't get very much access to sensitive areas of the castle, it is true, but chances are someone will notice our heroine's talents and give her a promotion, or else that she'll have a knack for attracting Exact Eavesdropping. If the infiltration has some sort of assassination in mind, kitchen staff have a perfect opportunity to poison people. If there's a ball, promotions can go quite high.

If she's simply hiding out, believe me, no one suspects that The Chosen One is sweating over boiling potatoes.

Even if she's basically been enslaved into such a position, the Scullery Maid will find some way to prevail. Contrast with Meido, Maid of Sexy, and Ninja Maid for less realistic interpretations of the role. For reference, the scullery is a small, hot, sweaty room behind the kitchen, where heavy, dirty, menial work, such as cleaning pots and pans, is carried out.

Examples of Scullery Maid include:

Fairy Tales

Cap O'Rushes, having been thrown out by her father for saying she loved him like she loved salt, went for such a job.
Joseph Jacobs's "Catskin" as a Runaway Fiancee

I’m sorry I have no better place, but if you like you may be our scullion.

"Katie Woodencloak":

Yes, the cook said she might have a place -- she might have leave to be there in the scullery, and wash up, for the lassie who did that work before had just gone away.

"Rashin Coatie" after running away from home.
"All-Kinds-of-Fur":

All-Kinds-of-Fur, thou wilt be useful in the kitchen, come with us, and thou canst sweep up the ashes.

"The King Who Wished Marry To His Daughter"

"If I could get," said she, "leave to go to service to this great house yonder." "They want none," said the herd, "unless they want one under the hand of the cook." The herd went to speak for her, and she went as a servant maid under the hand of the cook.

In "Catherine and Her Fate", Catherine, having chosen to be miserable in youth and happy in old age rather than the other way round, ends up as a Scullery Maid—except that her Fate, being an Anthropomorphic Personification, is always showing up and wrecking her position for seven years.
There is a class of fairy tales, related to "Cinderella", in which a princess is forced to flee her homeland and hides out as a scullery maid in the royal castle of another kingdom (and then the prince of that kingdom holds a ball in order to meet eligible young women, and so on). The episode "Sapsorrow" of The Storyteller is adapted from one of these.

Literature

In A City in Winter, the long-lost child queen takes a tip from La Résistance and takes a rather exhausting job sorting yams. Her subsequent rocketing through the ranks is heavily implied to be, quite literally, divine intervention.
The heroine of The Catswold Portal seems aware of this trope, but unfortunately for her, the evil queen interrogates every last member of the staff personally. (She dodges it well enough to complete her mission in the castle, but the added difficulties end up making the story halfway a romance.)
A Song of Ice and Fire actually plays this more or less straight with Arya.
- Shae, on the other hand, rejects the archetype, as she actually became a whore in the first place in order to stop working in a kitchen.
Lessa in Dragonriders of Pern starts out as a drudge with a very overdeveloped sense of vengeance. It takes years for her to finally get a chance at her foe, though she does enact loads of scorched-earth policies in the interim.
This was popular with Kunoichi. See That Other Wiki.
In The Chinese Maze Murders, Dee plants a spy in one household by sending her to get a job as a temporary maid.
Discworld:
- In Monstrous Regiment, this is how the heroes get inside the castle (including the male lieutenant, who is the most enthusiastic of them all).
- Nanny Ogg uses this as a highly successful infiltration technique. She's at home around people; knows their names, their family trees and everyone's maladies after about half an hour, and knows that nobody ever questions a little old lady being helpful, because it's a job you don't have to do and nobody cares if she doesn't get paid.
- Esk uses the classic Scullery Maid approach to infiltrate Unseen University, although her actual job is sweeping floors, not preparing food.
Lalasa in the Protector Of The Small series (by Tamora Pierce) started as a Scullery Maid before becoming Kel's personal maid.
Ella Enchanted has the title character assume this position in her own home after her obedience curse is discovered by her stepsisters. The job is given by none other than Ella's own fairy godmother, who works as a cook for the family and pretends indifference towards her godchild in order to protect her from being forced into a much lower position.
In A Little Princess, Sara Crewe takes this role to pay her headmistress.
In David Eddings' The Belgariad, powerful sorceress Polgara hides herself and the Chosen One as a cook for a rural farm and her nephew/scullery boy. This works ..sort of. Asharak apparently knew where Garion was the whole time, and they leave because Brill's found out where they are.
Egwene in Wheel of Time is held prisoner in this position to keep her out of the way and break her back into being a novice. It gave her even more power than when she was forced to redo classes.
In Patricia A. McKillip's The Book of Atrix Wolfe, Saro, after the magic had rendered her mute and dazed.
In The Secret Garden, Mary's first relationship in her new home is with the young scullery maid who comes to clean the fireplace in her room. Mary can't do anything for herself (having always been waited on hand and foot) and the girl takes pity on her and helps her learn to be self sufficient.
In The Ordinary Princess, Princess Amy runs away to the neighbouring kingdom to live in the forest. After wearing out her clothes, she decides to get a job as a scullery maid in the castle, and there meets the king.

Web Comics

In Erstwhile, both Maid Maleen and All-Furs get these jobs.

Western Animation

Stewie from Family Guy makes a comment that his new neighbor Eliza talks "like a scullery maid".
Henchman 21 from The Venture Brothers reveals in a counselling session that he was part of the "scullion class" of The Monarch's army.