Mayhem Family was a team of skilled thieves in Gotham City and is a villain in the Batman Beyond series.
Ma Mayhem, the matriarch, had a husband whom she pulled numerous heists with. Her husband later left Ma for another woman, leaving their sons in her care. She pretends that her husband was dead but her sons remind her peculiarly. She was, at some point, sent to jail but escaped with her sons. Ma Mayhem later stole ruby jewels as they were the first swags that she stole with her husband. Mayhem and her sons broke into the Museum of Fashion when they fought Batman (Terry McGinnis). They later overcame Terry and fled the museum and carried Terry's Eggbaby in their truck. Terry used the Eggbaby to track down the criminal trio.
Batman faced Ma Mayhem again and saved the Eggbaby. Ma Mayhem tried to escape with the stolen rubies but was captured by Batman and sent back to jail.
But this would not be the last time Batman/Terry would see them: Ma Mayhem and her sons also appeared in Batman Beyond #19: Royal Mayhem, where they kidnap Princess Vinishri of Uganistan.
Her two sons are named Carl and Slim. Carl acts as the muscle of the Mayhem family but not very bright. Slim acts as the family's safe cracker and aims for bigger things. Understandably Slim follows his mother in her criminal activities, though somewhat reluctantly. He disliked his mother's plan to only steal the jewelry, while instead they could have stolen items worth so much more than that.
Ma Mayhem is similiar to Ma Barker.