We've all heard the metaphor that books are a gateway to other worlds. Sometimes, this stops being a metaphor and becomes the literal truth. A book is an ideal object to turn into a Cool Gate to a Magical Land. Portal Books usually come in one of three varieties: Any of these three may or may not overlap with Refugee From TV Land, when literary characters come through a Portal Book into "the real world." The best candidates for such reverse travel are villains. Compare Portal Door, for doors that lead someplace non-adjacent. Examples of Portal Book include: