This book explores the reception of the medieval Irish tradition of fantastic journey tales in Jonathan Swift’s Gulliver’s Travels, C.S. Lewis’s The Voyage of the Dawn Treader, Umberto Eco’s Baudolino, and the science fiction television franchises Star Trek and Stargate. In doing so, the book opens the door to a new history of literary reception, using Old Irish genre categories to analyse post-medieval texts. It aims to show that there is a family of texts produced in the post-medieval period that are heirs of the medieval Irish literary tradition of fantastic voyage narratives and that using Old Irish genre categories to analyse post-medieval works can open up new perspectives in our understanding of these works.