They are many kinds, living and dead, unliving and undead. They have no common appearance, merely a common purpose.
They are the Lamplighters. They maintain the lights on every major intersection in Necropolis.
Each has a different ritual for doing this, from oiling rusty bits to speaking a lengthy incantation. These come from the individual lamplighter's past, and despite their vast number, there are very few whose rites are the same.
They all have their own reasons for doing this; if you wish to know, ask them yourself.
Most Lamplighters are eccentric at best; some are quite mad. The truly stable and sane ones tend to have been dead for Wheels upon Wheels.
No exact count has been made. They have no leader, no organizing hierarchy. If you wish to join, start lighting lamps.
Primus-Of-The-Lamps was the first lamplighter. Primus-Of-The-Lamps set the original lamps into place, to shed light and some minor comfort upon those who feared the dark. Primus-Of-The-Lamps is now a lamp, giving light, comfort, and advice to those who journey within the darkness. Primus-Of-The-Lamps does not need to be lit, for the light will always shine from within.
Most Lamplighters are masks.