Holly Hills' is Gregory's crush. She was first mentioned in Rodrick Rules. Holly Hills real birthday is January 26. She loves to play tennis and swim in pools with diving boards like in dog days. She is the younger sister of Heather Hills, and also the youngest daughter of Mr. Hills and Mrs. Hills. She is the wife of Howard Hills, the sister-in-law of Jesse Hills, the maternal aunt of Jessica Hills, the mother of Maurice and Melissa Hills, and also the youngest granddaughter of Mason and Monica Hills. Holly Hills is portrayed by Peyton List.
Holly Hills was born and raised in Ponyville together with her older sister Heather. She and Heather were taught various martial arts by their maternal grandfather Mason Hills since young age. Holly was also personally trained by her maternal grandmother Monica Hills. When Mason died under mysterious circumstances the siblings blamed each other over his death, leading an endless rivalry between the two. After this, both siblings went to their separate ways.