Fancy Pants

Fancypants is a Canterlot high society unicorn pony that is introduced in the episode Sweet and Elite. Rarity describes him as the most important pony in Canterlot, and indeed, his opinions seem to be heeded as unwritten laws by the other pony nobility; his entourage frequently change their opinions to agree with his own.

History
He first appears when Rarity bumps into him and a white/pink mare (known as Elizabeth or Fleur-de-lis by the fandom) while walking through the streets of Canterlot. She instantly recognizes him as "The most important pony in Canterlot" and apologizes for running into him. He takes an interest in her when she mentions she is staying at Canterlot Castle by invitation of the Princess and invites her to his private box at the upcoming Wonderbolts Derby. He becomes more interested in Rarity after she correctly predicts the winner of the derby, and insists that she must be extremely important after she lies about knowing the trainer of the Wonderbolts (she claims Rainbow Dash is their trainer).

He is seen during Rarity's song montage, in many of the social events and on what is thought to be his personal yacht.

Later on, Fancypants greets Rarity at a garden party next to the room where Twilight's birthday party is taking place. Rarity's friends crash the event when Twilight "realizes" that Rarity wants to attend it, and subsequently offend many of the upper class ponies with their raucous partying. While Twilight is dancing to music, Fancy Pants stops her to ask about the dress she is wearing, which Rarity had made but never finished. Twilight proclaims Rarity as the designer, and Fancypants is again favourably impressed with her, and gives it as his opinion that "every mare in Canterlot will be wanting one".

Personality
Despite being a pony of high social status and breeding, he differs greatly to many of the more shallow and uppity blue-blooded Canterlot Ponies by his amiable and tolerant personality. Throughout his appearances in the episode, he is kind, thoughtful, and benevolently condescending to Rarity, as well as accepting of her friends and their "rustic charm", which Upper Crust and Jet Set dismissed as "ruffian" behaviour. He also seems to carry a wider palet for fashion than other Canterlot ponies, as he expresses an interest in Rarity's more complete designs as well as the simple, half finished dress that Twilight was wearing for her party, even before he knew that Rarity had made it. He sometimes contradicted the stuffy, uppity mannerisms of his fellow blue bloods in order to spare Rarity's feelings.

Trivia

 * "Fancy pants" is an informal term that means overly elaborate, swanky or pretentious.
 * His voice seems to be an imitation of actor David Niven.
 * Fancypants and his white/pink mare resemble the great U.S. "Wheel of Fortune" host "Pat Sajak " and hostress " Vanna White"