Last expansion the order hall leaders were NPCs lorewise, there was only one player leader, you... Look at the quest where you use your artifact to drain power out of Sargeras' sword, named lore characters are holding all the class artifacts except yours. Eitrigg has Strom'kar, Liadrin has the Ashbringer, Valeera has Garona's daggers, Rehgar Earthfury has the Doomhammer, Darion Mograine has Apocalypse.
Canonically only one PC, you, is an order hall leader.