Gwendolyn Tennyson (Ben 10 UAF)

Gwen Tennyson is Ben's 17-year-old, super-powered, energy-controlling cousin. While she considers her cousin Ben to be her best friend, Gwen has strong, unspoken feelings for Kevin Levin, the bad boy of her dreams. In addition to her black belt-level martial arts skills, Gwen can manipulate energy by creating solid shapes to use as shields or tentacles, fire powerful energy blasts from her hands, and track people or objects by detecting their energy resonance known as "manna" the hidden mstic energy that permeates all of nature. But there's an even deeper secret behind Gwen's powers than she ever realized until the meeting with her grandmother!

Ben 10 Ultimate Alien Force
She is one of the main heroes.