Teen supernatural horror from the 80's

I was going through some old books and remembered a series of books that I read as a teen in the early to mid 80's. They were all really creepy but very well written. All the books were stand alone but involved the same characters, usually teens hunting for some supernatural object or event. Some elements of them that I remember:

-Artifacts involved - a splinter from Jesus' cross; the finger bone of a skeleton
-Bad guys - one book had a zombie type character; another had a fear-inducing skeletal humanoid (with a pumpkin head maybe?)
-May have had Gorey-style art on the cover and within

I'm trying to remember more details - I'll add more as they come to me.

Dark Forces?

Where Darkness Begins?

Hey, I found it! It's the books by John Bellairs; The Dark Secret of Weatherend was one that I was thinking of.

So glad you found it! Thanks for coming back to let us know.

Touchstone fairy: The Dark Secret of Weatherend