Mary-Beth has married at least six times, and her marriages have ended with her husbands dying gruesome deaths; with her taking part in most, if not all. She wears either pants or dresses, as she mentions wearing them interchangeably as well as mentioning the fact that she wears bloomers. She also has numerous children and broadcasts from Bone County, which is a desert region near Las Venturas. Mrs. Maybell is never seen in person, only heard on the radio. Sometimes, Mary-Beth puts a harmonica in her pants to make music, a talent she learned while in a women's prison.
During the course of her frequent marriages, she managed to give birth to 9 children, which some of them are going through puberty (Mary-Beth mentions one of them going through a "natural transition to womanhood"). The weirdest of her stories about her children came when Mary Ellen (probably the oldest of the 9 children) was born on a pool table and the players kept on playing. Mary-Beth is also said to be heavy-set, which she reveals after Juice Newton's "Queen of Hearts" song.
Mary-Beth is voiced by Riette Burdick.