I'm probably going to be playing in a Phoenix Academy game of Masks, a playset detailed in Masks Unbound. So who or what would I play? Here's some of my ideas, in (roughly) playbook order.
Beacon: "Happy Phantom", inspired by Tori Amos' "Happy Phantom". This character ran away from an abusive home after suddenly developing phasing and invisibility powers, and thinking that they had become a ghost. They're still not sure they're really alive, and they're okay with that.
Brain/Doomed: Detox, inspired by John Henry Irons. An inventor who just wanted to be liked by their friends, so they created a drug that grants superpowers. That drug is now on the streets, being used by evil people, and only Detox can stop it for good. The Brain version uses an exo-suit and transforming robot buddy, while the Doomed version uses their own drug system to gain a variety of powers, at the expense of their life and health.
Harbinger/Nomad: Re-Pete, inspired by "Edge of Tomorrow". A character caught on the Threads of Fate, who is forced to jump around through time and space, reliving the same things over and over again and trying their hardest just to save everyone. The Harbinger version focuses on knowledge gained from the time-loops, while the Nomad focuses on tricks picked up along the way.
Innocent: Andrew Belmont, who as an adult hunted a powerful vampire and was turned into one himself. Young Andrew was brought forward through sorcery as insurance against his older self's actions by the Order of St. Marcel. However, as a Belmont, he can't let evil go unpunished... even if it means facing his older self, or the original vampire he was hunting! (see also the Scion)
Janus: "Mezmer", inspired by Mictlāntēcutli and the Fortnite skin. A character who strongly believes in justice, with bone control powers (including forming a mask out of an extension of their own skull). However, they are the child of a senior school administrator, who would probably try to steer their superheroic activities. So they want to keep their ID a secret from their parents.
Legacy: "Armiger", inspired by the movie "Creed". Imagine the Green Lantern Corps, only instead of rings of power, they wield echoes of the sword Excalibur and uphold noble ideals. Armiger himself is a black sheep among the Grail Knights, and swings a sword his own way.
Newborn: Here, inspired by Danny the Street. The genius loci or awakened spirit of the school, or the neighborhood in which it's set. They are interested in learning more about people, and constantly changing their presentation and actions to match. Their caretaker is a senior student or teacher.
Outsider: "Tag", inspired by graffiiti and "What Dreams May Come". A visitor from a parallel dimension connected to ours via street art, who can pop in and out of such art and wield the power of animated paint.
Protégé: "Scrapper", inspired by "Big Guy & Rusty". A gadgeteer and inventor who rebuilt an old android superhero and is now training under them as a powered-armor hero.
Reformed: Rivet, inspired by Medaka Box's Kumagawa. A cheerful former villain who used ferrokinesis powers to rob banks and commit purposeless terror, he was brought to heel by a powerful and influential hero - perhaps a fellow student. Now he tries to figure out what it means to be forgiven, or to care.
Scion: Ash Hawthorn, "child" of a powerful vampire. Ash has no wish to follow in their monstrous maker's footsteps, and enlists the aid of heroes capable of defeating this evil. While good-hearted, they are still haughty and aristocratic, and not immune to the thirst of their kind. (see also the Innocent)
Transformed: "Captain Marble". A jock who made a wish on a monkey's paw to have "the perfect body, you know, like those statues of Greek gods". They got their wish, alright.