Theoretical chapters map existing fan studies research and develop new theoretical perspectives of fandom by bringing fan studies, play theory and mediatization theory together. Theory chapters are paired with case study chapters providing comprehensive, in-depth-analysis of fandoms from the US, UK and Scandinavia as examples of different play moods and playful practices in a transmedia perspective.Empirical examples are taken from a wide range of media, including television (e.g. Sherlock, SKAM, Gilmore Girls etc.), musicals (e.g. Hamilton Musical, Dear Evan Hansen), podcasts (e.g. Pod Save America, Serial), politicians (e.g. Bernie Sanders, Barack Obama, Donald Trump), films series (e.g. Harry Potter, Star Wars, The Avengers) and media platforms such as Twitter, YouTube, Tumblr, Reddit, Facebook, Instagram, and Archiveofourown.