The A-list is the informal top tier of celebrity: the people whose names open films, fill rooms and bring invitations without asking. Merriam-Webster dates the phrase to 1935, and it has since produced a whole alphabet below it, from the B-list downwards, which nobody ever admits to being on.
Hollywood has occasionally tried to make the hierarchy scientific. The entertainment journalist James Ulmer built his Hollywood Hot List around bankability, the power of a star’s name alone to get a film approved, and gave each actor a score from 1 to 100 based on factors such as talent, professionalism, career management and willingness to travel. One edition, reviewed in 2000, opened with an A-plus group that included Julia Roberts, Tom Cruise and Tom Hanks. Everywhere else the A-list remains gloriously unofficial, which is precisely why it can be argued about at dinner forever.