An A-list celebrity is one at the very top of their field. It may be a bankable movie star, a major recording artist, international sports star, social media personality, film director, mogul, or an international TV broadcaster.
The A-list is part of a larger guide called The Hot List that has become an industry-standard guide in Hollywood. James Ulmer, the creator of The Hot List, has also developed a Hot List of Directors. The Ulmer scale categorizes the lists into A+, A, B+, B, C, and D listings.