Answer
Synonyms: Unnoticeable, Unmark able, Hidden
Antonyms: Noticeable, Conspicuous, High-profile
Explanation
For example
John played an inconspicuous (Unmarkable; Unnoticeable) role in the school.
She hoped, she would not look inconspicuous (not inconspicuous = noticeable) so her fans would approach her at store
