Just joking with the Snapper Carr line.
Yeah, the line can get blurry. Though Morbius is a Science Fiction Vampire introduced in a superhero book, rather than a supernatural one. I suppose that how I draw the line: "point of origin". If they're introduce in a superhero title, I'm more inclined to think of them as superheroes.
Although Morbius went on to star in
Vampire Tales and
Adventures Into Fear, and has battled Blade, which also demonstrates just how blurry things can get. And where do we put Ghost Rider or Son of Satan? Or The Demon?
When you're dealing with universes in which Spider-Man has teamed up with Werewolf By Night, and the X-Men have fought Dracula more than once, and where Constantine recently fought the JLA for possession of Pandora's Box . . . well, it's not like either Marvel or DC has ever tried to keep their horror and superhero lines from mingling.
Trying to remember if Blade has ever teamed up with Spider-Man or the Defenders, but my memory is failing me.
Ooh, here's another interesting case: Moon Knight's very first appearance--his "point of origin" as it were--was in WEREWOLF BY NIGHT, but it's hard to deny that he's regarded mostly as a superhero now. Heck, I think he was even an Avenger at one point . . . .