The next film set in the magical world will be Fantastic Beasts and Where to Find Them, which is set 70 years earlier than the modern-day Harry Potter films. Presumably this will cover everything from dragons to hippogriffs to flobberworms, or at least mention them. But going by Professor Lupins lectures on Dark Creatures in his DADA lessons, or Hagrids views on the various monsters hes loved over the years, there are an awful lot of dangerous, non-sentient creatures out there that Muggles dont know about. None of these creatures would be able to determine whether the human theyve just encountered is a wizard or not, and theyre extremely unlikely to kowtow to the Ministry laws governing such creatures. There are also a lot of sentient magical beings that would cause a great stir in the Muggle world if they were revealed: centaurs, goblins, house elves, giants, veela, leprechauns, vampires, etc. We Muggles are convinced that we are the only sentient class on the planet; this kind of knowledge could start wars to rival the bloodiest in our history. Ron does mention in The Philosophers Stone that, our lot have to keep putting spells on Muggles whove spotted them (dragons), to make them forget. This must keep the folks at the Accidental Magical Reversal Squad extremely busy. But how do they know when a creature has been spotted? Does an alarm bell go off in their office every time it happens?