Twinkleshine

Twinkle is the placeholder name for a female unicorn pony with an off-white coat, pink mane and tail, electric blue eyes, and a cutie mark of three sparkly blue stars. She shares her design with Lemon Hearts. She has a speaking role in Friendship is Magic, part 1, which is the first spoken line of any background pony in the show. Her design resembles that of the G1 pony Moondancer.

Depiction in the series
Twinkle is fairly commonly featured in the series as a background pony, appearing in over half the episodes in season 1. Her first and most prominent appearance is in Friendship is Magic, part 1, where she, Lemon Hearts and Minuette meet Twilight Sparkle in Canterlot while carrying presents on their backs. She informs Twilight about Moondancer's get-together and asks her to come along. When Twilight declines on the grounds that she has "a lot of studying to catch up on", Twinkle expresses her exasperation behind Twilight's back and chides her for showing more interest in books than friends. She next appears in the surprise party that Pinkie Pie throws for Twilight later in the episode, and has since then remained a regular sight in Ponyville.

In The Ticket Master, she is one of the ponies crowding around Twilight in front of the library, and again in the alley Twilight eventually teleports away from. A handful of frames show her starting to run after Twilight, but she is not part of the throng of background ponies in the chase scene that follows. During her two-second participation in the race, her mane style changes to one resembling Cherry Berry and "Berry Punch's".

In The Cutie Mark Chronicles, she appears in Fluttershy and Rainbow Dash's flashbacks of flight camp, standing on a cloud in the sidelines before the race starts, even though she is not a pegasus.

Appearances
Times stated below are approximate and taken from videos available online.

Merchandise
A unicorn pony named Twinkleshine was released as both a mystery pack figurine and a Playful Pony toy in 2010. The toy shares Twinkle's cutie mark, eye color, and mane color except for the darker streak. The coat color, on the other hand, is pink in contrast to Twinkle's off-white.

Quotes

 * Twinkle: There you are, Twilight. Moondancer is having a little get-together at the west castle courtyard. You wanna come?
 * Twilight Sparkle: Oh, sorry, girls. I got a lot of studying to catch up on!
 * Twinkle: Does that pony do anything except study? I think she's more interested in books than friends.
 * — Friendship is Magic, part 1