Big Cheese is an informal phrase used to refer to someone important, influential, or powerful. Antonyms for this phrase might include "nobody," "minor," "nonentity," "inferior," or "loser." These words are often used to describe individuals who lack importance, influence, or power. Big Cheese is an idiom that can be used to describe someone who has authority or control within their field, whereas the antonyms suggest a lack of importance or influence. It's important to keep in mind that the use of any term, including Big Cheese, will depend on the context of the situation and the speaker's intent.