antagonist
n//ænˈtæɡənɪst//antagonist, motståndare
An opponent or enemy.
(biochemistry) A chemical that binds to a receptor but does not produce a physiological response, blocking the action of other agonist chemicals, such as endogenous chemical messengers.
(authorship) The main character or force opposing the protagonist in a literary work or drama.
(anatomy) A muscle that acts in opposition to another.