Meteora Butterfly

Meteora Butterfly is the Mewman-Monster hybrid daughter of Eclipsa and Globgor, and the true heir to Mewni throne, having been replaced with a peasant girl named Festivia by the Magic High Commission and Eclipsa's ex-husband King Shastacan, as revealed in "Butterfly Trap". Raised by the robot headmistress Olga, who named her "Heinous" after hearing Shastacan's insult, Meteora forgot her identity while eventually taking over as headmistress of St. Olga's Reform School for Wayward Princesses with the support of her robot assistant Gemini and the Septarian bounty hunter Rasticore Chaosus Disastervaine. But she later is forced out of St Olga's when deposed by Star and Marco, bearing a grudge on them. In season 3, starting off the events that reveal the High Magic Commission's actions in covering up her existence, Meteora accidentally stumbled upon her childhood home during the events of "Monster Bash" and regained her memories as a result. Meteora later forces her way back into St. Olga's in the events of "Skooled!", ripping Pony Head's horn off after learning the full truth of her heritage with aspirations of claiming her birthright as ruler of Mewni. Gradually transforming into a giant soul-sucking monster, Meteora is ultimately turned back into a baby by Eclipsa in the season three finale.