An agonist is a substance that binds to a receptor and activates it, producing a biological response. In pharmacology, agonists can refer to drugs that mimic the action of naturally occurring substances in the body, such as hormones or neurotransmitters. They can enhance or facilitate a specific physiological effect, making them important in various therapeutic applications. For example, morphine is an agonist that binds to opioid receptors to relieve pain.
The agonist (not angonist) muscle are the Biceps Brachii and the Brachioradialis and the antagonist is the Triceps Brachii.
The main antagonist of the Harry Potter Series is Lord Voldemort aka The Dark Lord, He-Who-Must-Not-Be-Named, You-Know-Who, and Tom Marvolo Riddle.