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. She 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. It is likely that she ended up in prison from killing one of her six husbands.
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's surname may come from Mother Maybell of the Carter Family, although she implies this may not be her real surname.
Mary-Beth appears to be concerned about the gang situation in Los Santos as at one point early in the game she can be heard asking why the different gangs can't just get along.
The six body-bags found in the hole are thought to contain the dead bodies of Mary-Beth's six deceased husbands. The bodies themselves were supposedly dumped there by Mary-Beth after she murdered her husbands. She says this after the song All My Exes Live in Texas by Whitey Shafer, in which she says "All my ex's are six feet under." She also says she drives a truck.
Mary-Beth is voiced by Riette Burdick.