After years of on-off tension and negotiations, one of the most important voice actors on the iconic animated series will reportedly not be returning.

Harry Shearer, the voice behind  Mr. Burns, Principal Skinner, Waylon Smithers, Ned Flanders, Reverend Lovejoy, Kent Brockman, Dr. Hibbert, Lenny Leonard, Rainier Wolfcastle, Otto Mann among others, tweeted the following:

Twitter

At the root of the issue--which some sources, such as CNN Money, are calling a holdout, rather than a quitting or a firing--is Shearer's desire to do outside work. This has not been an issue in the past, as indicated by his prolific resume; in addition to his extensive work on The Simpsons, Shearer is also known for his involvement in film (one of the driving forces behind This is Spinal Tap and the other Christopher Guest movies), music, documentaries, and hosting a popular weekly radio show, Le Show, which airs on NPR affiliates.