Princess Erroria

Princess Erroria is the placeholder name of a female Pegasus pony with a vanilla coat, wisteria mane and tail, and blue irises. Despite her placeholder name, she is not depicted as a princess in any official material. Depending on the episode, her cutie mark is either a single pink flower, a white feather, a horseshoe, or nothing at all, and she appears as four different kinds of pony, including as an Alicorn due to an animation error. Princess Erroria also shares her design with "Cotton Cloudy" and "Tornado Bolt".

Depiction in the series
Princess Erroria appears several times in both seasons 1 and 2 as a non-speaking background filly. She debuts at Diamond Tiara's cute-ceañera in Call of the Cutie, where she displays the flower and feather cutie marks. Her unicorn version appears in Twilight's imagine spot in Lesson Zero with the addition of wings due to an animation error. An Earth pony version appears in A Friend in Deed during Pinkie Pie's Smile Song and in Apple Family Reunion going on the hayride (occasionally with wings). Her unicorn version appears again in both Just for Sidekicks and Games Ponies Play walking with Daisy at the Crystal Empire train station.

She is dressed as an astronaut in Luna Eclipsed without a cutie mark, and she is also shown receiving candies from Twilight alongside "Noi" and "Piña Colada". Princess Erroria also competes in the Sisterhooves Social with "Cloud Kicker". She is shown giving a Hearts and Hooves Day card to Diamond Tiara in Hearts and Hooves Day as well. She appears in The Mysterious Mare Do Well as a fan of Rainbow Dash and watches Apple Bloom in a crowd in The Cutie Pox.

She also appears in Ponyville Confidential, Apple Family Reunion, Just for Sidekicks, Games Ponies Play, Magical Mystery Cure, Pinkie Pride, Simple Ways, Filli Vanilli, Twilight Time, It Ain't Easy Being Breezies, For Whom the Sweetie Belle Toils, Leap of Faith, Inspiration Manifestation, and Equestria Games.

Appearances
Times are approximate and taken from videos with no prolonged transition for commercial breaks.