Maggie however did say "Good night" in Good Night, the very first Simpsons short on the Tracey Ullman show broadcast on April 19, 1987, her voice provided by As Told By Ginger's Liz Georges and during one of the Halloween episodes, she was an Alien/Human crossbreed and had the voice of James Earl Jones. "Her" line was "This indeed is a disturbing universe", said after she chopped an axe down onto Groundskeeper Willie. There is also another ep, Flaming Moe's, where Homer thought he heard her say "Moe", and another where, "playing pat-a-cake" with the power plant's security system, a sleepless Homer thought that she had said her first words (remember that he never heard her say "Daddy", from above).
See: Characters from The Simpsons