Ralph Wiggum is a recurring fictional character on the animated series The Simpsons, voiced by Nancy Cartwright. The son of Police Chief Wiggum and a classmate of Lisa Simpson, Ralph is best known as the show's resident oddball, and is noted for his non sequiturs and erratic behavior. His lines range from nonsensical, or bizarre interpretations of a current event, to surprisingly profound statements that go over people's heads; and his behavior varies between blissfully unaware, to dim-witted, to awkwardly spontaneous, even occasionally straightforward. The very nature of the character has undergone seemingly differing interpretations over the years and within various media.

The creator of the show, Matt Groening, has cited Ralph as his favorite character. He generally remains one of the more popular and often quoted secondary characters in the show.

Ralph is an awkward but good-natured 8-year-old boy in Lisa Simpson's second-grade class taught by Ms. Hoover. Although his beginnings were that of a tertiary child character along the same lines as Lisa's on-and-off friend Janey, he has since become one of the more prominent secondary characters on the show, even being the focus or at least a major character of some episodes.

Nancy Cartwright (born October 25, 1957) is an American film and television actress, comedian and voice artist. She is best known for her long-running role as Bart Simpson on the animated television series The Simpsons. Cartwright voices other characters for the show, including Nelson Muntz, Ralph Wiggum, Todd Flanders, Kearney, and Database.

Born in Dayton, Ohio, Cartwright moved to Hollywood in 1978 and trained alongside voice actor Daws Butler. Her first professional role was voicing Gloria in the animated series Richie Rich, which she followed with a starring role in the television movie Marian Rose White (1982) and her first feature film, Twilight Zone: The Movie (1983).

After continuing to search for acting work, in 1987 Cartwright auditioned for a role in a series of animated shorts about a dysfunctional family that was to appear on The Tracey Ullman Show. Cartwright intended to audition for the role of Lisa Simpson, the middle child; when she arrived at the audition, she found the role of Bart—Lisa's brother—to be more interesting. Matt Groening, the series' creator, allowed her to audition for Bart and offered her the role on the spot. She voiced Bart for three seasons on The Tracey Ullman Show, and in 1989, the shorts were spun off into a half-hour show called The Simpsons. For her subsequent work as Bart, Cartwright received a Primetime Emmy Award for Outstanding Voice-Over Performance in 1992 and an Annie Award for Best Voice Acting in the Field of Animation in 1995.