The Hitchhiker's Guide to the Galaxy Book Series by Douglas Adams

 

Originally a radio series, The Hitchiker's Guide to the Galaxy  by Douglas Adams was first published in book form in October 1979. The universe eventually expanded to include five books and has inspired television and film adapations.
Follow the adventures of everyman hero Arthur Dent whose perfectly ordinary Thursday afternoon takes a bizarre turn when he discovers his best friend is, in fact, an alien and that planet Earth is about to be demolished to make way for a hyperspace express route.