FILE: Harry Shearer Leaves The Simpsons After 25 Years LOS ANGELES, CA - JULY 24: Actor Harry Shearer arrives at the Los Angeles premiere of 20th Century Fox's "The Simpsons Movie" held at the Mann Village Theaters on July 24, 2007 in Westwood, California. (Photo by Kevin Winter/Getty Images)

When Phil Hartman died in 1998, "The Simpsons" retired his characters, including washed-up actor Troy McClure. The same happened with Bart's teacher, Edna Krabappel, after the death of voice actress Marcia Wallace in 2013.

But Harry Shearer's characters won't be retired so easily. The long-time Simpson's voice actor announced on Twitter that he won't be back for Seasons 27 and 28 of "The Simpsons." Shearer says he left over a disagreement about his freedom to do other work, including radio and stage acting.

This chart by Jishai Evers of Dadaviz shows just how many of the Simpsons' cast of characters Shearer is responsible for. (Click on the chart to enlarge.)

Shearer's 23 characters include Otto, Dr. Marvin Monroe, Kent Brockman, Judge Snyder, McBain, Mr. Smithers, Reverend Lovejoy, and some of the show's most important antagonists: Principal Skinner, Ned Flanders and, of course, Montgomery Burns. As Michael Cavna writes for the Post, many of his characters are men who "were often selling you something — frequently the belief in their own shaky authority."

Shearer's characters won't disappear; the show is already recasting new voice actors to play the characters. But it won't be quite the same the next time Mr. Burns orders his lackey to "Release the hounds."