Gwendolyn "Gwen" Tennyson is an Anodite Plumber, Ben's paternal cousin and was a main member of his team until her departure with Kevin in The More Things Change: Part 1.

In the first season of Alien Force, she wore a white shirt under a dark blue sweater, black tights under a black miniskirt, and black high heels. Her hair had also grown longer and was down to her waist.