a big cheese
An important, successful, or influential person. Jacob thinks he's a big cheese now that he's been promoted to assistant manager. I'm the big cheese around here, so you have to do what I say.
a big cheesemainly BRITISH, INFORMAL
If you describe someone as a big cheese, you mean that they have an important and powerful position in an organization. Maire is undoubtedly the big cheese of the Jura wine producers. Several big cheeses from the State Department attended the conference. Note: Big cheese can also be used before a noun. He was a big-cheese divorce lawyer. Note: The word `cheese' in this expression may be a corruption or misunderstanding of the Urdu word `chiz' or `cheez', meaning `thing'. This started being used in English in about 1840 because of the British presence in India. Later the word came to refer to a person or boss.
a big cheesean important and influential person. informal
Other versions of this phrase substitute fish , gun , noise , shot , or wheel for cheese . These are mainly self-explanatory, with the exception of cheese itself, which is of doubtful origin but may be from Persian and Urdu chiz meaning ‘thing’. As a phrase, big cheese seems to have originated in early 20th-century US slang, as did big noise. Big wheel in this metaphorical sense (as opposed to the fairground ride known as a Ferris wheel) and big shot are similarly US in origin (mid 20th century). Big fish may have connotations either of something it is desirable for you to catch or of the metaphorical expression a big fish in a small pond .