MLP D&D: Rarity

Name: Rarity
Race: Unicorn pony
Alignment: Neutral Fabulous
Class: Rogue

They say she's Ponyville's chief fashionista and dressmaker. But it's all a cover for her real role: Mistress of the Thieves' Guild. Just look at her cutie mark for verification: It's not a dress, or anything at all to do with fashion, but three diamonds.  Like any good rogue, Rarity loves the loot. Don't you remember that time she tried to rob a dragon's hoard -- right under his nose, no less -- by convincing him he looked good enough to be seen by everyone and that she was trustworthy enough to guard it for him?

Sure, she says she only uses her unicorn magic of gem detection to adorn her dresses, but really now, how many of those dresses have you seen bejeweled with bling? I've only ever seen one. And yet at the end of A Dog and Pony Show, she and the rest of the fillies are hauling back wagonloads of jewels.

It's all a cover, I tell you. The skill is real, but the dressmaking shop is just a front. Know what else you can make with exquisite sewing skills? Disguises. Elaborate disguises so cunning you won't realize you've been fooled until it's too late. Everything she does is to further her goal of getting into the Royal Court of Canterlot.

You see, she's not a common thief. She doesn't skulk about in shadows, or sneak attack, or pick locks (although with her unicorn telekinesis she'd probably be good at that.) No, Miss Rarity is a social rogue. Her main skills are Appraise, Bluff, Craft: Sewing, Disguise, and Knowledge: Nobility. Her ultimate goal? To marry into royalty by seducing Prince Blueblood, the (distant) nephew of Princess Celestia. 

I would stroll through the gala, and everyone would wonder: "Who is that mysterious mare?" They would never guess that I was just a simple pony from little old Ponyville. Why, I'll cause such a sensation, that I would be invited for an audience with Princess Celestia herself. And the princess would be so taken with the style and elegance, that she would introduce me... to "him"... her nephew! The most handsome, eligible unicorn stallion in Canterlot. Our eyes would meet... Our hearts would melt... Our courtship would be magnificent. He would ask for my hoof in marriage, and of course I would say... "YES!!!". We would have a royal wedding, befitting a princess which is... (giggles) what I would become upon marrying "him"... The stallion of my dreams!
-- Rarity's speech from The Ticket Master

She's trying to pass herself off as nobility, I tell you, and marry into even higher royalty. And then what happens? She loots the royal treasury of Canterlot.

Behold the Queen of Bling.

 
Still don't believe me? Look, she has a white cat for a pet. If that doesn't scream out "mastermind" then you're beyond convincing.

To summarize:

• High Intelligence, Wisdom, Charisma and Dexterity (Multiple Attribute Dependency is typical for Rogues).
• Strength is her dump stat (although someone in comments suggested Constitution).
• Exceptionally good at searching for treasure finding gems.
• Can bluff like the best of them.
• You'd never, ever suspect her. 

Key "Rarity is a Rogue" episodes:

• Tries to steal a dragon's hoard right out from under him in Dragonshy
• Uses cunning and manipulation to be set free -- with all the loot -- after being captured by the Diamond Dogs in A Dog and Pony Show
• Performs Uncanny Dodges in The Elements of Harmony as well as the aforementioned episodes
• Utilizes her Disguise skill dressmaking ability in Suited For Success
• Displays large-scale social manipulation abilities in Green Isn't Your Color