1. What Happened To Dale Cooper? - Twin Peaks
It shouldn't be a surprise that one of the biggest WTF endings in TV history comes at the hands of legendary weirdo David Lynch's show Twin Peaks. In the final episode, the show's protagonist, FBI Agent Dale Cooper, remains on the trail of the supernatural entity responsible for Laura Palmer's murder, Killer Bob, and ends up being possessed by it in the final scene. After entering a mysterious locale called The Black Lodge, Cooper has to face down an evil version of himself, and as is revealed in the final scene, only the evil one made it out, as Cooper smashes his head into the bathroom mirror and grins, revealing a reflection of Bob in the glass. Lynch doesn't seem that keen to clue us in on what happened next; the follow-up movie, Fire Walk With Me, was mostly a prequel, and though the idea of another series is teased regularly - reportedly with a possessed Cooper now walking around Twin Peaks - it's probably never going to come fruition. Which agonising mystery do you want answered the most? Let us know in the comments below.