Gwen Tennyson is Ben’s cousin and is present on the camping trip where Ben discovers the Omnitrix. Gwen is the same age as Ben.

Gwen uses her laptop to research any strange people and creatures they might come across. She is a capable gymnast and has had some training in martial arts. We later learn that Gwen has an innate ability to master magical powers and artifacts. In Ben 10: Alien Force Gwen is 15 years old and has developed the ability to use energy constructs to create anything she pleases. She regularly creates a platform that she can levitate on. Her abilities are discovered to have been inherited from her Grandmother, who was from Alien Descent. As the series progresses Gwen become infatuated with Kevin 11.

Gwen toys are available at several toy retailers. She is also available in a handy Ben 10 Starter Pack from Tesco Direct.