Nickelodeon TWST?

Guys I wanna come up with a Nickelodeon version of TWST, but I need characters for the Great Seven! I need five more. Any suggestions? (They do not need to be the villain of the show, but just very rememberable/iconic)

Either animated or live-action characters are fine!

Characters so far: Jewel Sparkles (Lalaloopsy), and Jade West (Victorious)