Official Harry Potter Slytherin Bookmark This bookmark has been created using the official style guide from Warner Bros. One of the famous Hogwarts Houses, founded by Salazar Slytherin Stainless Steel This bookmark comes on the Official Harry Potter branded card packaging and shows the Warner Bros logo on the reverse. This bookmark is one of many new Harry Potter Bookmarks we offer as a part of a collection. The Carat Shop are the official licensed manufacturers of Harry Potter Jewellery on behalf of Warner Bros.