The Simpsons
Shearer is known for his work as a voice actor on The Simpsons. Matt Groening, the creator of the show, was a fan of Shearer's work, while Shearer was a fan of a column Groening used to write. When approached by Groening to be in the series, Shearer was initially reluctant because he thought the recording sessions would be too much trouble. He felt that voice acting was "not a lot of fun" as, traditionally, voice actors record their parts separately. He was told that the actors would record their lines together, and after three phone calls for executive producer James L. Brooks, Shearer was convinced to join the cast of The Simpsons. Shearer's first impression of The Simpsons was that it was funny. He thought it was a "pretty cool" way to work but found it peculiar that his fellow cast members were adamant about not being known to the public as the people behind the voices.
Shearer provides voices for Principal Skinner, Kent Brockman, Mr. Burns, Waylon Smithers, Ned Flanders, Reverend Lovejoy, formerly Dr. Hibbert until 2021, Lenny Leonard, Otto Mann, Rainier Wolfcastle, Scratchy, Kang, Dr. Marvin Monroe, and Judge Snyder, among others. He has described all of his regular characters' voices as "easy to slip into. ... I wouldn't do them if they weren't easy." Shearer modeled Mr. Burns's voice on the two actors Lionel Barrymore and Ronald Reagan. Shearer says that Burns is the most difficult character for him to voice because it is rough on his vocal cords and he often needs to drink tea and honey to soothe his voice. He describes Burns as his favorite character, saying he "like[s] Mr. Burns because he is pure evil. A lot of evil people make the mistake of diluting it. Never adulterate your evil." Shearer is also the voice of Burns' assistant Smithers, and is able to perform dialogue between the two characters in one take. In the episode "Bart's Inner Child", Shearer said "wow" in the voice of Otto, which was then used when Otto was seen jumping on a trampoline. Ned Flanders had been meant to be just a neighbor that Homer Simpson was jealous of, but because Shearer used "such a sweet voice" for him, Flanders was broadened to become a Christian and a sweet guy that someone would prefer to live next to over Homer. Dr. Marvin Monroe's voice was based on psychiatrist David Viscott. Monroe has been largely retired since the seventh season barring a few cameo appearances because voicing the character strained Shearer's throat.
In 2004, Shearer criticized what he perceived as the show's declining quality: "I rate the last three seasons as among the worst, so season four looks very good to me now." Shearer has also been vocal about "The Principal and the Pauper" (season nine, episode two, 1997), one of the most controversial episodes of The Simpsons. Many fans and critics reacted negatively to the revelation that Principal Seymour Skinner, a recurring character since the first season, was an impostor. The episode has been criticized by both Shearer and Groening. In a 2001 interview, Shearer recalled that after reading the script, he told the writers, "That's so wrong. You're taking something that an audience has built eight years or nine years of investment in and just tossed it in the trash can for no good reason, for a story we've done before with other characters. It's so arbitrary and gratuitous, and it's disrespectful to the audience." In a December 2006 interview, Shearer added, "Now, [the writers] refuse to talk about it. They realize it was a horrible mistake. They never mention it. It's like they're punishing [the audience] for paying attention."
Due to scheduling and availability conflicts, Shearer decided not to participate in The Simpsons Ride, which opened in 2008, so none of his characters have vocal parts and many do not appear in the ride at all. In a 2010 interview on The Howard Stern Show, Shearer alluded that the reason he was not part of the ride was because he would not be getting paid for it. Similarly, Shearer was unable to appear in the Family Guy crossover episode "The Simpsons Guy" due to further scheduling conflicts. Therefore, his characters are again mute. When asked about how he felt about the crossover, Shearer replied, "Matter and anti-matter."
Until 1998, Shearer was paid $30,000 per episode. During a pay dispute in 1998, Fox threatened to replace the six main voice actors with new actors, going as far as preparing for casting of new voices. The dispute, however, was resolved and Shearer received $125,000 per episode until 2004, when the voice actors demanded that they be paid $360,000 an episode. The dispute was resolved a month later, and Shearer's pay rose to $250,000 per episode. After salary re-negotiations in 2008, the voice actors received $400,000 per episode. Three years later, with Fox threatening to cancel the series unless production costs were cut, Shearer and the other cast members accepted a 30% pay cut, down to just over $300,000 per episode. On May 14, 2015, Shearer announced he was leaving the show. After the other voice actors signed a contract for the same pay, Shearer refused, stating it was not enough. Al Jean made a statement from the producers saying "the show must go on," but did not elaborate on what might happen to the characters Shearer voiced. On July 7, 2015, Shearer agreed to continue with the show, on the same terms as the other voice actors.