Wallace's agent confirmed the news Saturday to Eyewitness News but would not comment further on the cause of death or give any other details.
Wallace was best known for her work on the long-running FOX animated show as Bart Simpson's crabby teacher at Springfield Elementary. She was also a regular on the 1970s comedy sitcom, "The Bob Newhart Show." She played Carol Kester, the lovelorn and wise-cracking receptionist.
Wallace also made appearances on Candice Bergen's "Murphy Brown."
"Simpsons" executive producer Al Jean said in a statement Saturday that her death is a terrible loss. He says Wallace's "irreplaceable character" would be retired from the show.
The Associated Press contributed to this report.