The Hitchhiker's Guide to The Galaxy
What started out as a scifi radio broadcast in the late '70s evolved into a multimedia phenomenon inculding books, a text adventure game, a tv show, and of course the 2005 film. HGOTG is packed with a cast we would each watch individually in just about anything, and while your mileage with it may vary, there's no denying that the source material offers a delightfully slanted take on space-borne sci-fi.
Why GOTG fans will dig it: If Alan Rickman voicing Marvin the Paranoid Andriod isn't enough of a reason (the character has a Radiohead song named after him. Come on!); every character is pretty much a hot mess, which is exactly what makes them all so funny.