Eclipsa's older daughter
Still with Globgor
She has highly evolved magic (way past star and doesn't need a wand)
She somehow got out of a crystal when star is sent to earth or shortly after
Disguises herself as a high school student and becomes friends with Marco and Star
Moves in with the Diaz's and goes on adventures with Marco and Star while discreetly practicing her magic (everyone thinks she's a regular human)
She's the one who ends up stopping Meteora instead of Eclipsa
She has long red violet hair that she tends to have in two French braid ponytails.
She has horns and a tail that she learned to hide with her magic.
Every mention of her was erased completely (like Eclipsa only had one daughter)
I think her name could be something like Andromeda or a constellation name but she goes by "Nova"
I just love the name Nova and using a longer name makes sense because she's a few hundred years old (having been put in the crystal shortly after her mother)