How alien may creatures be, so that we are still able to communicate with them? What are the conditions for successful communication? And: What could we expect to find out with such a communication? The maximal stranger, the subject which the authors of this book investigate, is always the non-human opposite: gods and ghosts, angels and demons, extra-terrestrials and artificial intelligences. They are entities, with which communication, interaction and even the most general assumptions, on which we can usually rely even with the most foreign human cultures because of supposed anthropological absolute terms, fail. Accordingly, theoretical as well as empirical requirements for the disciplines in search for possibilities and limits of communication with the maximum stranger are very high. This is one reason why answers given by sociologists, ethnologists, literary and media studies, theology and computer sciences tend to be so diverse. Nevertheless, what they all have in common is the wish to help to understand what is seemingly not understandable.