Olivia Jane d'Abo (pronounced /ˈdɑːboʊ/; born 22 January 1969) is an English actress and singer-songwriter, best known for portraying Karen Arnold in The Wonder Years and Nicole Wallace, the recurring villain in Law & Order: Criminal Intent.
d'Abo's film debut was in the supporting role of Princess Jehnna in Conan the Destroyer, released in June 1984. Just two months later, she also appeared in the supporting role of the peasant girl Paloma in Bolero, in which she had a controversial nude scene - she was fourteen at the time the movie was filmed.
From 1988, d'Abo was in the main cast of The Wonder Years in the first four seasons. Her character "Karen Arnold" was the hippie sister in the family. In 1992, she guest starred in the Star Trek: The Next Generation episode "True Q" as Amanda Rogers. As the recurring villain Nicole Wallace, she made five appearances over a six-year period on television crime-drama Law & Order: Criminal Intent. On the Sci-Fi Channel series Eureka, she has the recurring role of Abby Carter, ex-wife of Sheriff Jack Carter.