>>114327657I feel like there was a bunch from the previous threads that didn't get added to the images yet.
The Whistler
Dr. E. Leopold Maas (from Kirby's Spirit World and DC's Weird Mystery Tales)
Judge Gallows (from DC's The Unexpected)
Squire Shade (from DC's Ghosts)
Speaking of Squire Shade, in an issue of Ghosts he has a Ghostly Coachman that looks like The Shadow. Since I assume the Horrorverse Shadow is based on him being a radio host/horror host, you can pretend that is him and add that as part of the Horrorverse Shadow backstory.