coryphaeus

noun3

1. •
   The leader of an opera chorus or another ensemble of singers.
2. •
   (historical) The conductor or leader of the chorus of a drama.

   • Then the coryphaeus finishes the remaining part of the strophe. But when they have returned to order, Bacchus again interposes by beginning the antistrophe β', which the coryphaeus ought to have done. — 1830
3. •
   The chief or leader of an interest or party.

   • Of the work which I have done, it becomes me not here to speak, save only as relates to the Satanic School, and its Coryphaeus, the author of Don Juan. — 1822