Forgetting Any Other Book But This

Those sites that allow readers to recall hazy memories of books are always interesting. If anything it gives us the chance to welcome them to Bellairsia and experience John’s (and Brad’s) work again.

I'm looking for a series of horror books I read as a kid. They have black and white covers. I remember only bits and pieces of the names of the characters. I do remember that often the main character was named "Johnny" and a "Professor Childress" (I believe). They often dealt with demons and things of that nature. The cover of one of them was a drawing of a boy looking at a mask on a street at night.

Another book by the author was about a girl that went back in time (I believe) and she was also a recurring character. Most of the antagonists were demons.