Hitchhikers’ Guide fills in a much needed void in Sci-Fi; that of the long form comedy.
I know of nothing else like it, outside of the works of Stanslaw Lem. The trilogy actually has five novels in it, but the later novels merely expound on concepts presented in the first two. These were also made into an entertaining, “Dr Who” looking BBC television series which was further altered extensively for a Hollywood movie. The series also endured as a radio serial. Beaten to death themes of alien invasion, galactic warfare, and interstellar travel are all given a fresh treatment by Adams‘ British wit. Some real science by way of cosmology has been dropped in, too: The Big Bang, Fermi’s Paradox, and the conundrums of time travel are all represented here. And this book manages to do another remarkable thing; it draws in fans who otherwise would have nothing to do with science fiction!