agonist vs antihero

agonist and antihero both are nouns.

Word	Noun	Adjective	Verb	Adverb
agonist	Yes	No	No	No
antihero	Yes	No	No	No

As nouns, antihero is a hyponym of agonist; that is, antihero is a word with a more specific, narrower meaning than agonist:

agonist: the principal character in a work of fiction
antihero: a protagonist who lacks the characteristics that would make him a hero (or her a heroine)

agonist (noun)	antihero (noun)
(biochemistry) a drug that can combine with a receptor on a cell to produce a physiological reaction	a protagonist who lacks the characteristics that would make him a hero (or her a heroine)
a muscle that contracts while another relaxes
someone involved in a contest or battle (as in an agon)
the principal character in a work of fiction