Gwendolyn Catherine "Gwen" Tennyson is a Human / Anodite hybrid Plumber, Ben Tennyson 's cousin from his father's half of the family, and (along with Kevin Levin) was a front line member of his team during the first 3 shows. Gwen was first introduced when her parents sent her on a summer-long road trip with her Grandpa Max and her cousin Ben.