Harry Julius Shearer (born December 23, 1943) is an American actor, comedian, musician, radio host, writer, and producer. Born in Los Angeles, California, Shearer began his career as a child actor. From 1969 to 1976, Shearer was a member of The Credibility Gap, a radio comedy group. Following the breakup of the group, Shearer co-wrote the film Real Life (1979) with Albert Brooks and worked as a writer on Martin Mull's television series Fernwood 2 Night.

Shearer was a cast member on Saturday Night Live (SNL) between 1979 and 1980, and 1984 and 1985. Shearer co-created, co-wrote and co-starred in the film This Is Spinal Tap (1984), a hit satirical rockumentary. In 1989, he joined the cast of the animated sitcom The Simpsons, providing voices for characters including Mr. Burns, Waylon Smithers, Ned Flanders, Reverend Lovejoy, Lenny Leonard, Kang, Principal Skinner, Kent Brockman, Otto Mann, Scratchy, and formerly Dr. Hibbert. Shearer has appeared in films including The Truman Show (1998) and A Mighty Wind (2003), and has directed two, Teddy Bears' Picnic (2002) and The Big Uneasy (2010). Since 1983, Shearer has been the host of the public radio comedy/music program Le Show, incorporating satire, music, and sketch comedy. He has written three books.

Shearer has won a Primetime Emmy Award and has received several other Emmy and Grammy Award nominations. He has been married to singer-songwriter Judith Owen since 1993. He became an artist in residence at Loyola University, New Orleans in 2013.

Shearer was born December 23, 1943, in Los Angeles, California, the son of Dora, a bookkeeper, and Mack Shearer, a trained opera singer who ran a gas station. His parents were Jewish immigrants from Poland and Austria respectively. His parents escaped Nazi-occupied Europe and met in Havana, Cuba. As a child, Shearer and his family often listened to radio programs such as Bob and Ray and the weekly show for the Jewish Theological Seminary of America. His father died when he was 12 and he had his Bar Mitzvah the following year. Shearer grew up in the neighborhood of West Adams. Starting when Shearer was four years old, he had a piano teacher whose daughter worked as a child actress. The piano teacher later decided to make a career change and become a children's agent, since she knew people in the business through her daughter's work. The teacher asked Shearer's parents for permission to take him to an audition. Several months later, she called Shearer's parents and told them that she had gotten Shearer an audition for the radio show The Jack Benny Program. Shearer received the role when he was seven years old. He described Jack Benny as "very warm and approachable ... He was a guy who dug the idea of other people on the show getting laughs, which sort of spoiled me for other people in comedy." Shearer has stated that one person who took him "under his wing" and was his mentor during his early days in show business was voice actor Mel Blanc, who voiced many animated characters, including Bugs Bunny, Daffy Duck and Barney Rubble; Blanc was a regular on The Jack Benny Show. He also befriended Blanc's son Noel. Shearer made his film debut in the film Abbott and Costello Go to Mars (1953), in which he had a small part, and appeared in The Robe (also 1953). Throughout his childhood and teenage years, he worked in television, film, and radio.

In 1957, Shearer played the precursor to the Eddie Haskell character in the pilot episode of the television series Leave It to Beaver. After the filming, Shearer's parents said they did not want him to be a regular in a series. Instead they wanted him to just do occasional work so that he could have a normal childhood. Shearer and his parents made the decision not to accept the role in the series if it was picked up by a television network.

In the summer of 1960, Shearer volunteered as a driver for the Democratic National Convention during the 1960 United States presidential election where he was regularly assigned trips to Disneyland.

Shearer graduated from Los Angeles High School and attended UCLA as a political science major in the early 1960s. He decided to quit show business to become a "serious person". However, he says this lasted approximately a month, and he joined the staff of the Daily Bruin, UCLA's school newspaper, during his first year. He was editor of the college humor magazine (Satyr), including the June 1964 parody Preyboy. He also worked as a newscaster at KRLA, a top 40 radio station in Pasadena, during this period. According to Shearer, after graduating, he had "a very serious agenda going on, and it was 'Stay Out of the Draft'." He attended graduate school at Harvard University for one year and worked at the state legislature in Sacramento. From 1967 to 1968, he was a high school teacher, teaching English and social studies. He left teaching following "disagreements with the administration".

From 1969 to 1976, Shearer was a member of The Credibility Gap, a radio comedy group that included David Lander, Richard Beebe, and Michael McKean. The group consisted of "a bunch of newsmen" at KRLA 1110, "the number two station" in Los Angeles. They wanted to do more than just straight news, so they hired comedians who were talented vocalists. Shearer heard about the group from a friend, so he brought over a tape to the station and nervously gave it to the receptionist. He found out he was hired that same day. The group's radio show was canceled in 1970 by KRLA and in 1971 by KPPC-FM, so they started performing in various clubs and concert venues. While at KRLA, Shearer also interviewed Creedence Clearwater Revival for the Pop Chronicles music documentary.