Diamond Tiara is a minor villain from the Character What franchise, She is also a character from My Little Pony: Friendship is Magic.
Character What: Tales
In G3,5 Scootaloo Meets G4 My Little Pony, Diamond Tiara catch up with G3 Scootaloo and saw that she was drinking milk from a baby bottle, Diamond Tiara started to tease her, G3 Scootaloo then spit milk at her a few times, Then G3 Scootaloo hit her on the head with her bottle.
In Spiderman Meets My Little Pony, Diamond Tiara laugh when Spiderman web Apple Bloom on a tree, When Diamond Tiara was laughing, Spiderman throw her and web her on a tree like he did with Apple Bloom.
In Joker Meets My Little Pony, Batman or Apple Bloom throw Diamond Tiara at the Joker.
She make a cameo in Rapunzel Meets My Little Pony, When She was teasing Apple Bloom by calling her a "Blank Flank" a few times. Rover accidentally throw a bee hive at her head, and when the bee hive was on her head, she went running around screaming.