Billy's mother and Harold's wife is a loving, tolerant, and patient, yet mentally unstable woman brought on by having to deal with her family, and Grim as an eternal guest. Gladys has red hair and is usually seen wearing a floor-length, lavender dress. She considers Grim a constant threat to her son's safety. In multiple instances, Gladys is seen attacking Grim to protect her son. She has a severe facial tic, which usually appears when Billy is misbehaving, when her authority is challenged, or whenever Grim is present, and has also developed nervous breakdowns. Despite so, Gladys cares deeply for Billy and Harold, although when Harold gets fired for doing something so stupid or whenever Billy is really disobeying her or acting up, she does have large outbursts of rage like hunting Harold with a harpoon in the movie. She reaped owls using Grim's scythe due to losing her pet rat, Sniffles (framing Grim was also an extra bonus (for her) to get rid of him from the house) (though it was Harold who ate the rat and possibly her goldfish). She wants Billy to grow up to be a chiropractor, even though she knows that is very unlikely to happen. She is prone to small fits of insanity and obsessive-compulsive episodes. Because of all of the stress caused by Billy, Harold, Grim and, to a lesser extent, Mandy, in her everyday-life, Gladys is the only character in the series to demonstrate having more control over herself when Mandy uses her own will power.