I created these ghost pop-up book as a cute Halloween centerpiece on my table. You can take an old book page and draw ghost shapes on two pages. I did them freehand, but you can use the below free ghost pattern printable if you would like a stencil or pattern to trace.
Then cut out the ghosts and draw some eyes or facial expressions with black marker. You could also punch holes for eyes. Finally create a pile of books with one open in the middle and tape your ghosts up onto the pages using a thin strip of card stock, cardboard or thick paper in the back to prop them up from behind.