The name of the cemetery in Hocus Pocus where Billy Butcherson and Emily Binx is buried is called Old Burial Hill. Here is a link to the Old Burial Hill Cemetery in Marblehead.
Old Burial Hill
There is at least one gravestone with a skull and crossbones like the one on Billy's tombstone. It belongs to Margaret Hawkins (1761). If you use the site map, you'll find her stone on The Cluster by the Pond — 3 (Pond Cluster -3 ). It's at the bottom of the page.