Just barely avoided by Brittany Murphy's character in King of the Hill, which ended in September 2009 - Murphy died of exposure to toxic mold in December of the same year. Especially with Luanne becoming a mom.
There are four episodes that were finished but did not make it into the final season of King of the Hill. These, aired in May 2010 on Adult Swim, were specifically held over just in case another network planned on picking it up. But now...
Didn't stop the series when Victor Aaron, the original voice of John Redcorn, died in an auto accident after the first season. He was replaced by Jonathan Joss.
And the death of Tom Petty, the voice actor of Lucky, makes a revival even more unlikely.
Phil Hartman's characters Lionel Hutz and Troy McClure on The Simpsons were retired out of respect, and though they have occasionally been seen in the backgrounds of scenes, neither have had speaking appearances since.
Similarly, he was the original choice to play Zapp Brannigan on Futurama, but died before the first episode aired. Billy West based parts of his performance on Hartman's, and the creators then named Philip J. Fry after him.
Also, a number of scenes in Small Soldiers, released later that year, involved guns being aimed at his character. These scenes were removed because the creators realized that it would have been in poor taste, especially considering how he died.
Similarly, The Simpsons retired Lunch Lady Doris for many years due to the death of her voice, Doris Grau, but in recent years she's speaking again (courtesy of Tress MacNeille), unlike Hutz and McClure.
Kathleen Freeman, the voice of Ms. Gordon in As Told by Ginger, died before she finished her role in the episode "No Hope for Courtney". As a result, the character she played passed away instead of getting out of retirement. The whole episode was dedicated to the voice actor.
Mary Kay Bergman, who originally voiced most of the female characters on South Park (including Mrs. Marsh, Mrs. Broflovski, Mrs. McCormack, Mrs. Cartman, Wendy, etc.) had suffered from depression for years and committed suicide just after finishing recording her parts for the show's third season. "Starvin Marvin In Space" and "Mr. Hankey's Christmas Classics" were dedicated to her memory.
Tony Jay was the voice of Megabyte, ReBoot's Big Bad. The series ended on a cliffhanger with Megabyte in the Principal Office, and then Tony Jay died. Who knows what Rainmaker will do if they continue the series.
Long John Baldry was the voice of guest star Captain Gavin Capacitor, and he died as well.
Toy Story 3 and 4 features Slinky Dog, formerly voiced by Jim "Ernest P. Worrell" Varney, who died in 2000. Varney's friend Blake Clark supplied Slinky's voice for the third and fourth films.
Also, Wheezy the penguin doesn't feature in both films: both his speaking (Joe Ranft) and singing (Robert Goulet) voices had died by the time the films was made.
Mr Potato Head lost his voice actor Don Rickles during early production of the fourth film. With his family's blessing, Disney were able to use achieve recordings of his character's lines from previous works. This explains why Mr Potato Head and the rest of the other Toys (with the exception of Buzz) were demoted to extra in the fourth film.
Lyricist Howard Ashman died in the middle of the production of Aladdin, leaving Tim Rice to supply lyrics to "One Jump" and "A Whole New World." Tim Rice was called on for the Screen to Stage Adaptation of Beauty and the Beast for the same reason.
After Mako Iwamatsu, the voice of Aku in Samurai Jack and Uncle Iroh in Avatar: The Last Airbender died in 2006, Greg Baldwin took over as the new voice of the character in the darker and edgier 5th season on Adult Swim.
Avatar: The Last Airbender was able to get by with Baldwin doing a quite good impression of him for Uncle Iroh. Rather eerily, the show's creators claim that they had always planned to have Iroh not speak in his first couple appearances in season 3. That ended up giving them some extra time to find a replacement, which they eventually found with Baldwin.
After the death of Fred Willard, who voiced Pop-Pop in The Loud House, Pop-Pop's fate was left up in the air for a while. It was eventually resolved when the character had his first speaking role since his death in "Resident Upheaval", where he was voiced by Christopher Swindle. The role was then permanently recast to Piotr Michael starting with "High Crimes".
It's unknown who will take over from the late Joe Alaskey as the new voice of Plucky Duck for the Tiny Toons reboot on HBO Max. For his role as Grampa Lou Pickles in the Rugrats reboot on Nickelodeon/Paramount Plus, Michael McKean took over the role.
Will Ryan, the longtime voice of Willie The Giant, died on November 19, 2021. It's currently unknown who will replace him. In an eerie coincidence, an episode of Mickey Mouse Funhouse aired that day where he reprised the role.
