Alan Moore really, really hates Harry Potter. His Top 10 spin-off fantasy mini-series Smax features a field trip from a wizard school being horribly killed by a dragon because of their teacher's recklessness (a reference to common fan criticisms of Hogwarts staff's casual attitude to dangerous creatures). The League of Extraordinary Gentlemen: Century turns into an incredibly vitriolic denunciation of Potter as artistically and politically reactionary, with Harry massacring the entire rest of the Potter cast, turning out to be literally The Antichrist, and finally getting killed by Mary Poppins.
Live Action TV
The Big Bang Theory: In one episode Leonard reads the last book, and Sheldon and even Penny spoil several plot points for him.