Wallace, who voiced Bart's 4th grade teacher Mrs. Krabappel since the show's second episode in 1990, died Oct. 25 due to complications from
Wallace won an Emmy for playing Krabappel in 1992, and "Simpsons" producers have said they will retire the character rather than try to find someone new to play the role.
The new episode, which was also notable for its lengthy, "Hobbit"-inspired couch gag in the opening credits, was paired with a classic episode "The Ned-liest Catch," in which Wallace's character began dating widower Ned Flanders. The two characters later married.
"The Simpsons" has rarely completely retired any of its characters. Maude Flanders was killed in an episode in 2000. But the character has continued to return as a ghost or through flashbacks.