Monster High is an American fashion doll franchise created by Mattel and launched in July 2010. The characters are inspired by monster movies, sci-fi horror, thriller fiction, and various other creatures. Mattel began releasing a number of animated direct-to-videos, some of which have been broadcast as television specials and films on Nickelodeon. In 2015, the series released a reboot and origin story called Welcome to Monster High, using new face molds and animation. there's 15 of them so far and here's the list

1. Monster High: New Ghoul at School
2. Monster High: Fright On!
3. Monster High: Why Do Ghouls Fall in Love?
4. Monster High: Escape from Skull Shores
5. Monster High: Friday Night Frights
6. Monster High: Ghouls Rule
7. Monster High: Scaris: City of Frights
8. Monster High: 13 Wishes
9. Monster High: Frights, Camera, Action!
10. Monster High: Freaky Fusion
11. Monster High: Haunted
12. Monster High: Boo York, Boo York
13. Monster High: Great Scarrier Reef
14. Welcome to Monster High
15. Monster High: Electrified

https://en.wikipedia.org/wiki/List_of_Monster_High_films