Alien shape-shifter who was raised as a human, joined a super-hero team in her teens, fought lots of battles, made lots of trouble, became team leader, and learned of her true origins.

Monstergirl

Alien shape-shifter who was raised as a human, joined a super-hero team in her teens, fought lots of battles, made lots of trouble, became team leader, and learned of her true origins.

All data from the awesome folks at Marvel.