Mom (The Binding of Isaac)

Mom is the main antagonist of the video-game The Binding of Isaac and acts both as the Big Bad of the game as well as the Final Boss encounter, she is the mother of Isaac and is the central force of evil within the game.

Once a caring individual Mom went insane at some point and began to hear God speaking to her, telling her Isaac was evil and corrupt - Mom proceeded to deny Isaac basic rights and abused him horribly, locking him in his room, removing his clothes and denying him almost any form of nurishment or love.

Mom's madness then reached a climax when she became convinced God had ordered her to kill Isaac as a sign of her devotion and she prepared to make her son a sacrifice, despite being a despicable and evil woman Mom continually praised God and believed she was doing her Lord's work.

Mom also manifests in Isaac's nightmare world as a horrific demon that acts as the final monster he must encounter in the game, having a massive array of powers and being depicted as a mindless killer.