Danica Mae McKellar (born January 3, 1975), is an American actress best known for her role as Winnie Cooper in the television show, The Wonder Years.

Born in La Jolla, California, McKellar and sister Crystal McKellar have maintained a friendly competition to see who gets more acting jobs. In fact, when the actress who would play Winnie had to be chosen, the only two actresses who were still in competition were the McKellar sisters.

Danica and her family moved to Los Angeles when she was 8, and soon after, she and her sister began acting.

McKellar studied at UCLA, majoring in mathematics, and graduated summa cum laude in 1998. She coauthored a scientific paper1 which appeared in a peer-reviewed physics journal. Referring to the mathematical abilities of McKellar and her fellow student Brandy Winn, one of her math teachers, Professor Lincoln Chayes, was quoted in the New York Times2 as saying, "I thought that the two were really, really first rate". McKellar uniquely even provides free online math tutoring for her fans at her official internet website.

Since then, as well as several guest roles in television series (including one with former co-star Fred Savage on "Working"), she has written and directed two short films. She has returned to regular television with a role in The West Wing.

She appears in lingerie for a pictorial for the July 2005 edition of Stuff Magazine