What is Winnie Cooper's full first name?

Winnie Cooper's full first name is Gwendolyn.

Gwendolyn “Winnie” Cooper is Kevin Arnold's neighbor, close friend and principal romantic interest in the original The Wonder Years. She is played by Danica McKellar, and the nickname Winnie is used throughout most of the series.

Winnie's family storyline begins with the death of her older brother Brian, who is killed in Vietnam in the pilot episode. That tragedy affects her parents' marriage and helps establish the emotional connection between Winnie and Kevin. Later, Winnie travels to Paris to study art history, while she and Kevin continue writing to each other.

The name is sometimes misremembered as Winnifred or Gwendoline. Neither is the character's established first name: the series identifies her as Gwendolyn Cooper. She also should not be confused with Karen Arnold, Kevin's older sister.