Gwen Tennyson is the cousin of Ben Tennyson, wife of Kevin Levin as well as the mother of Devlin Levin and the adopted aunt of Tracy and Tricia. She is voiced by Tara Strong.
Gwendolyn has short orange hair that has bangs in the front. She wears a blue and black spandex suit and the Charms of Bezel on her right arm. She has a hood and only sometimes wears it. She has a belt with a cat on it, the same cat Gwen wore on her shirt when she was ten.
In Ken 10, Gwendolyn has much longer hair in a ponytail.
In Ben 10,000, 30 year old Gwendolyn came through a portal to the Main Timeline and grabbed Gwen to lead XLR8 into her timeline. When Ben and Gwen were there they believed the "crisis" Gwendolyn was talking about was Vilgax and Dr. Animo. At the end of the episode Gwen realized that Dr. Animo was never the crisis, Ben 10,000 just needed a major attitude adjustment.
In Ken 10, 42 year old Gwendolyn appeared as a hologram and gave Kenny a Stone Creature as a birthday present. Later in the episode, she and Ben 10,000 were discussing whether or not Ben 10,000 should let Ken fight.
Gwen appears in many MCF stories as well as Tracy 10 sharing a close bond with her adoptive niece Tracy as it is revealed in the MCF story Thanksgiving Mystery in a flashback, Tracy reveals to Serpentine that she had used a spell from Gwen's copy of Charmcaster's spellbook.
- Originally before deciding on Ben and Julie, Gwen was originally going to be Tracy and Tricia's adoptive mother but decided Ben would fit better.