who’s who - definition and synonyms

noun [singular] 

Your browser doesn’t support HTML5 audio

  1. a group of the most important people involved in a particular subject or activity
    a (regular) who’s who of something:

    The guest list read like a regular who’s who of the fashion industry.

Word story
From the name of the well-known book Who’s Who that gives details about the lives and achievements of important people.