Gwen Tennyson is a fictional character from the animated television series Ben 10. She is the cousin of the main character, Ben Tennyson, and is known for her intelligence and resourcefulness. Throughout the series, Gwen develops magical abilities, which she uses to help her cousin in battles against various villains. Gwen is characterized by her strong sense of justice and loyalty to her family and friends. She often acts as the voice of reason and provides support to Ben during their adventures. Her character evolves over the series, showcasing her growth and development as a hero in her own right.