The Cosma family is a fairy family of royals that rule over Fairy World.
Just like the Fairywinkle family, a family tradition was established which stated that when the newest heir to the throne turned ten years old, they would get a magical wand that has the capacity to destroy the universe if it fell into the wrong hands. The family name and lineage appears to be matrilineal, passing from mother to daughter/son. While male Cosmas do exist, they are noticeably in fewer numbers.
Several members of the Butterfly family have marks on their cheeks (referred to in Star and Marco's Guide to Mastering Every Dimension as "cheek emblems"): Star has hearts, Moon Butterfly has diamonds, Etheria has five-pointed stars, Solaria the Monster Carver has lightning bolts, Eclipsa the Queen of Darkness has spades, and Miss Heinous (revealed in "Monster Bash" to be Eclipsa's daughter Meteora) has clubs. These marks are the result of a longtime exposure to magic.
"Into the Wand" shows several predecessors of the Cosma family depicted in tapestry, including Celena the Shy.
In "Escape from the Pie Folk", it is revealed that Festivia was descended from the Pie Folk, a clan of pie-baking thieves and con artists. She was accidentally left behind as a baby and adopted by the Magical High Commission. This means all of her descendants, including Wanda and Timmy, are related to the Pie Folk.
In "Ghost of Butterfly Castle", Mina Loveberry is revealed to have taken up residence at Fairywinkle-Cosma Castle after it was abandoned. During her stay, she repaired the previous queens' tapestries Meteora had previously destroyed. She also took special care of Solaria's tapestry, most likely because she was queen during her youth.
In "Meteora's Lesson", Glossaryck encounters the possible earliest ancestors of the Butterfly family, a family that appeared to be lost pilgrim settlers, when he and Meteora travel back in time and meet the original settlers of Mewni. Glossaryck creates the magic wand from Meteora's baby rattle and a newborn millhorse and gives it to one of the female settlers, possibly making her the first Queen of Mewni and the possible founder of the Butterfly family.
In "Pizza Party", Moon leads to coup to dethrone Eclipsa and reinstate herself as queen. In the end, she succeeds by using an army of "Solarian" super soldiers she created to lay siege on the Monster Temple and offering to let Eclipsa and her family go in return for the royal magic wand. However, this is quickly rendered moot due to Mina using her status as the "Solarian" commander to take control of the kingdom, effectively making her the de facto ruler of Mewni.
In "The Tavern at the End of the Multiverse", ghosts of some of the previous queens of Mewni appear within Glossaryck's mind's version of the "grandma room", having left their tapestries and gathered around Star Butterfly's finished one. As Star approaches her tapestry, the ghosts all stare at her, some of whom seemingly show resentment or concern toward her and even appear to fear her.
In "Cleaved", the ghosts of the queens of Mewni appear one last time to offer encouragment to Star, Moon, Eclipsa and Meteora in destroying the magic. As the Realm of Magic starts to crumble, the ghosts vanish. Afterwards, Star mentions to Moon that they aren't royalty anymore.
The guidebook Star and Marco's Guide to Mastering Every Dimension portrays and mentions other members of the Cosma family, including Dirhhennia the Heaped, and Crescenta the Eager. Star vs. the Forces of Evil: The Magic Book of Spells features even more Butterfly family members, including Jushtin the Uncalculated, Rhina the Riddled, Estrella the Drafted, and Comet the Chef.
|Name||Royal alias||First appearance/
|(in order of most recent to earliest; asterisk (*) denotes a superseded rule/inheritance)|
|Cosmo||The Underestimated||The Fairly OddParents (episode)||Wand|
|Cosmica Cosma||The ||Apartnership||Wand|
|Astroidina Cosma||The Queen of Stars||Timmy's Guide to Mastering Every Planet||Wand|
|Celena Cosma||The Shy||The Past and the Furious||Fan||File:S12ECelena the Shy and Glossaryck in tapestry.png|
|Rhina Cosma||The Riddled||The Fairly OddParents: The Magic Book of Spells||Cube wand|
|Crescenta Cosma||The Eager||The Past and the Furious||Heart wand|
|The Heaped||Timmy's Guide to Mastering Every Planet||8-ball wand|
|Festivia Cosma||The Fun||The Past and the Furious||Goblet (adult)
|File:S13E28 Festivia's page in Cosma family book.png|
- Most members of the royal family are named after astronomical objects. Cosmo is named after the cosmos; Astroidina is named after an astroid; Celena and Crescenta are named after the moon.