Ok, I have searched quite a few “retro comic book” sites for any clue to this series. It appeared in horror comic books of the late 70s (at least that’s when I saw it.) It was a series that ran in the back of books like DC’s “House of Secrets” or perhaps a smaller (non-DC/Marvel) publisher back then.
Anyway, the feature centered around a mysterious “Madame X” who functioned a lot like the Phantom Stranger - she didn’t seem to have any origin, had a host of supernatural abilities and simply showed up out of the blue - or rather her “shop” would appear out of the blue - whenever she was needed.
I’ll give you an illustrative example that is based on my hazy recollection of one story - the story follows a normal, unassuming woman (let’s say her name is Jill.) Jill is the happy girlfriend of a charming young man (let’s say his name is Lance.) One day, Lance receives notice that a reclusive old uncle of his has died and bequeathed to him a painting. Lance is baffled as to why his uncle (who never seemed to like him) would send him the portrait, but nevertheless he hangs it up. Days go by, and Jill begins seeing a strange change in Lance’s behavior: he becomes irritable and secretive, associates with a new crowd of shady people, and seems completely obsessed with this painting he’s acquired. One night, Jill sees Lance acting very strange (performing a ritual) in front of his uncle’s portrait. Lance becomes violent and nearly slaps Jill. She flees in terror.
Distraught, Jill wanders the streets that have been filled with an ominous fog. She hears a voice beckoning her forward, coming from a storefront. “Strange!” thinks Jill “I’ve lived here for years, walked down this street almost every day…but I’ve never noticed this store before.” And so Jill enters the strange little curio shop of Madame X. The raven-haired Madame X’s dialogue balloons are all wavy lined to indicate that she has an ominous voice. Madame X tells Jill that she psychically sensed her troubles and offers to help. Jill then tells her all about Lance and the painting, and then Madame X goes into action.
Of course, Lance’s uncle was a satanist and had his soul placed in the portrait. Poor Lance was becoming possessed by his uncle’s spirit. The evil uncle intended to permanently take over Lance’s body by offering up a sacrifice to the devil - Jill! Madame X however saves the day, defeating the evil uncle’s ghost and the whole devil cult he belonged to, restoring Lance to normal, and rescuing Jill from being sacrificed. Happily reunited, Jill & Lance embrace - and while they were distracted, Madame X would disappear.
The story ends with Jill & Lance married, walking down the street one day. Jill thinks to herself “How odd! I’d swear that Madame X’s store was right here on this street - only it isn’t anymore!” Where the storefront was, there’s now a brick wall…or empty lot…or something to indicate that Madame X didn’t just clear out of the storefront, the whole building simply vanished.
Anyway, that was the basic model story - some everyday protagonist would find themselves caught up in a supernatural peril. They would “stumble” upon Madame X’s curio store, she would aid the protagonist in defeating the supernatural beings, and afterwards the protagonist would try to find Madame X’s store again - only to find the store gone!
Anyway, does this ring a bell with anyone? Or did I somehow just imagine reading this?
And if / when someone can corroborate this series’ existence, feel free to discuss any other long-forgotten series you might remember.