Diamond Tiara

Diamond Tiara is a baby pony who first appeared in Call of the Cutie and is the most popular pony at Apple Bloom's school. She and Silver Spoon are school bullies, who calls ponies without Cutie marks "Blank Flanks" and deems them not special.

Personality
Similar to girl bully stereotypes, Diamond Tiara makes fun of other ponies with cutie marks, who she and Silver Spoon call "Blank Flanks" and deems them of being not special.

History
In Call of the Cutie, Diamond Tiara and Silver Spoon invites Apple Bloom and another "Blank Flank", Twist, to their Cute-ceañera, a coming-of-age-like party to those who just earned their mark, so that they and the party attendees will make fun of both of them, or they don't show up at all. Twist manages to gain her cutie mark after finding her talent, but Apple Bloom hasn't gotten hers.

When Apple Bloom tried to hide herself (and her flank), from the ponies in the party with a table cloth, she bumped into the two guests of honor, Diamond Tiara and Silver Spoon. Diamond Tiara calls her bluff when Bloom lies that she got her cutie mark earlier, but Bloom saved face by saying she didn't want to show off and ruin the festivities. Diamond Tiara then claims that she didn't want to see Bloom's cutie mark anyways.

Unfortunately, as Apple Bloom prepared to leave, her disguise was caught and her bare rear was exposed for all the party attendants to see. Diamond Tiara and Silver Spoon didn't hesitate to make fun of Apple Bloom, but didn't expect two other "Blank Flanks" who hid at the party, Scootaloo and Sweetie Belle to defend Apple Bloom by saying that it just means that the three still have the potential to find their calling. Most of the other ponies at the party began to support Apple Bloom, Scootaloo, and Sweetie Belle, and despite Diamond Tiara claiming that the party was about her, her plan to make fun of Apple Bloom failed. She is seen watching the other ponies play the party activites from the stairway along with Silver Spoon.