Madame X is a mysterious woman who wants to trap Billy Joe Cobra's ghost in a jar for her collection of BJC memorabilia. Sam Hoover, the man who constantly tries to kidnap Billy, is her henchman acting under orders. Other than her schemes regarding Billy Joe Cobra, little else is known about her.
Her voice actress is unknown due to vague crediting.
Appearance
Madame X has purple hair, pale skin, and a gap between her front teeth. Her full face has never been shown.
Interestingly, none of the other characters know what she looks like, either. Billy's photos of her only involve her lower face and her purple-bangled hands.
Personality
Madame X seems to be a very cruel individual, seeing as she constantly mistreats Sam Hoover and has a desire to kidnap and store away Billy's ghost for her own purposes. She doesn't seem to regard others' feelings in any way, shape, or form. Judging by her behavior, Madame X is likely to be a sociopath.
Madame X moving on to "healthier pursuits".
She's also incredibly obsessive, evidenced by her fangirlish yet manic feelings toward Billy. This is a trait that is a genuine part of her personality. It cannot be removed, as seen in Billy's Achilles, when Hugh Wright acts as her life coach and she traps him inside her estate.
She appears to know the rules of being a ghost, having made sure to outfit her henchman in Billy Joe's underwear so that Billy is visible, and even having equipped him with a fully-functioning ghost containment gun.
Madame X may be a Southern belle. She has corn growing in her lair, she has been seen playing a banjo, and she was shown milking a cow while Hugh was acting as her life coach.
Billy Joe Cobra
Though Madame X herself can barely be seen from behind her large chair, it is apparent that she is a huge BJC fan. Her walls are covered in posters of Billy, her earrings are in the shape of Billy's face, and she knows every single obscure trivia fact about him, including his favorite animal, favorite food, and all the statistics regarding Billy's hit singles.
She is so crazy about Billy, she wants to capture him and put him in a jar as the crown jewel of her collection. Luckily for Billy, she never succeeds.
Communicating with Sam at her lair.
Sam Hoover
Nothing appears to irritate Madame X more than seeing her henchman fail at his job of collecting Billy. She has always been cruel to Sam, threatening to put him back on a diet of cat food if he does not succeed and yelling at him when Spencer Wright manages to foil their plans.
Regardless, Hoover seems to be incredibly devoted to her, suggesting that he thinks there is something good about her in his eyes. (No other character on the show would agree with him.)