Gwendolyn "Gwen" Tennyson is a Human/Anodite hybrid Plumber, the paternal cousin of Ben Tennyson, and (along with Kevin Levin, and during Ben 10: Omniverse, with Rook Blonko) a front line member of his team. Gwen was first introduced when her parents sent her on a summer-long road trip with her Grandpa Max and her cousin Ben. She has, as Verdona refers to it, "The Spark".