nemesis
/ˈnɛməsɪs/
An archenemy
Batman is in constant conflict with his nemesis, The Joker.
(chiefly non-North American usage) A person or character who specifically brings about the downfall of another person or character.
The principle of retributive justice.
(usually in the singular) A punishment or defeat that is deserved and cannot be avoided.
The polar opposite of a character.
A righteous infliction of retribution manifested by an appropriate agent.