Masked Lords Of WaterdeepΒΆ
The ruling lords or Waterdeep. There are about 20 members in total.
Each lord dresses in deep purple robes, edged with gold. They wear a half breast plate and helm with only a grill to see through.
It looks like some have also adjusted their height so they are all the same height, further obscurring their true identities.
The only unmasked lord is their leader, the Open Lord, currently Larell Silverhand.
It appears that there was an attack on them at The Field Of Triumph during the Arrival of the Worm Bois. After this attack, many of them fled in a large group, with a contingent of City Guards (or maybe Watch?). When they were ambushed by Worm Bois the Masked Lords were able to teleport away, their escort was not.